Uses 28 spline c-clip axles. All Revolution Ring and Pinion sets are backed by an industry leading 2 Year Warranty against defects. GM 8.5 Inch 10 Bolt 4.10 Ratio Dry 2-Cut Ring and Pinion Revolution Gear. Part Number: RMG-8310221 4.27 out of 5 stars It wasn't until late 1972 that the 10 bolt 8.5" ring gear was used in Chevelles. $226.20 $119.60 Add to cart View Yukon Master Overhaul kit for '64-'72 GM 8.2" differential . X Gear Ratio X 336 = RPM _____ Tire . 14-Bolt Axles as Upgrades to a 10-Bolt Axle. (Accurate identification using the GM RPO code assumes that the rear end has not been previously modified) The prefix is usually F, G or H when referring to . For example, a classic Muncie M22 four-speed with its 2.20:1 first gear needs a 4.11:1 rear gear to have a 9.042:1 final drive ratio for good acceleration, but highway cruising will be horrendous. Transaxle. Turning the tire for twice the number of full revolutions and dividing the drive shaft revolutions by two will give you a more accurate reading." Step 3. GM 8.5 Inch 10 Bolt 4.10 Ratio Dry 2-Cut Ring and Pinion Revolution Gear . The later model GM 8.5-inch 10-bolt differential is just such an option. The chart shown below shows RPM calculations at 55 MPHfor various combinations of final Gear Ratioand Tire Diameter. GM Vehicles come with a RPO code tag, usually located in the vehicles glovebox or door jamb. The BOM will identify the model number, the gear ratio, the type of differential, and all component parts. For my car 10 tire revolutions equals 33.6 driveshaft revolutions, so I have a 3.36 gear ratio. he said that yukon has discoutinued the the thin 5.13 gear sets, and if you are looking for a 5.13 gear your current axle must have 4.10 and numerically lower gears in it for the new 'thick' 5.13 gear set to work . Or if you know the ring gear ratio you want you can order your ring and pinion gears now on the strangeenginering.com website now. Keep in mind that in some applications the gear ratios might not calculate exactly, as is the case with 4.09, 4.10, and 4.11 gears and 4.30 and 4.31 gears. Identify the gear ratio, the build date, the plant where it was assembled the work shift when it was assembled, and positraction source - if equipped . The rear axle identification code consists of a two letter prefix indicating the gear ratio, four digits indicating the assembly date as month/day, and a single letter suffix indicating the manufacturing location. Revolution Gear and Axle GM 8.5 Inch 10 Bolt Ring and Pinion Gear sets are made from the highest quality steel and are precision heat treated to OEM specifications, making for the best aftermarket gears available. How To Install a Limited Slip/Posi Unit in a GM 10 Bolt 8.5″ Rear-end; How To Install Ring and Pinion Gears in a Ford 8.8 Rear-End; How To Narrow a Ford 8.8 Inch Rearend; How To Rebuild a GM 10 Bolt Chevy 8.5″ Rear End; How To Select Proper Rear-End / Differential Gear Ratio; Mopar Body Style Codes; Popular Automatic Transmission Dimensions 3.43 ratio: Pinion gear diameter decreases as the numeric gear ratio increases because there are fewer teeth on the pinion gear. More manual transmission information, including gear ratio and ID information, is located on the transmission page. Differential Identification. T. 10 bolt : Detroit gear & axle : GR : 3.08 : Yes (this code only used for . This tag, which is always present (if not removed by a previous owner), will indicate the gear ratio that came with the vehicle originally. 4.10,4.11,4.56 Ratios (Less internal gears) CASE, Diff. Ratio. GM Ring & Pinion Gear Set. Dana Spicer and Ford Differentials can be identified most accurately by the tag number or axle tube stamp. Save. $371.99. This is due to the slip present in an auto transmission's torque converter. But with a 3.06:1 first gear in a 700R4 automatic, you would only need a 2.96:1 rear gear for the same final drive ratio. This rear end was available in a 10 bolt version only. . This item GM Chevy 8.2" Chevy 10-Bolt Rearend Posi, Gear, Bearing Kit Package - 3.73 Ratio Yukon Gear & Axle (YDGGM8.2-3-28-1) 28-Spline Dura Grip Positraction for GM 8.2 Differential with 3.08 & Upward Axle Ratio The numbers should let you know what gear-ratio came from the factory, the date of production, where the unit was assembled, and whether the carrier is Positraction or not (see charts). The BOM stamp (2) or Axle Identification Tags (2A) are used to identify Dana axles / differentials. Both of these carriers used 10 bolts to retain the ring gear and should not be confused with the later 12-bolt 8.5-inch carriers. 8.5 inch 10-bolt. Our differential experts are available from 8am to 5pm PST Monday thru Friday. These differentials used a 12-bolt cover; the pinion was a 1.625-inch unit and had a 27-spline shaft. he said that yukon has discoutinued the the thin 5.13 gear sets, and if you are looking for a 5.13 gear your current axle must have 4.10 and numerically lower gears in it for the new 'thick' 5.13 gear set to work . One way to tell the 8.2 from an 8.5 is by the ring gear bolts. The following table contains a list of common aftermarket gear ratios. Hopefully this helps. Special heat treated R-50 High Impact ring and pinion sets were available in the 4.88 and . Before you start, you need to identify your parts. The last three numbers are the gear ratios. My rear is the bolt in axles. 2.76,3.07,3.21,3.40,3.42,3.73 Ratios (Less internal gears) 42 5.518 2402527 1 PIN . . Traditional BOM's are 6 digits followed by 1 or 2 digits and start with the numbers 60 or 61. . 0. i just talked with dunks performance out of springfield oregon. Yukon Gears are a high performance quiet gear, perfect for any GM 10 bolt 8.5" or 8.6" equip. The BOM will identify the model number, the gear ratio, the type of axle / differential, and component parts. RustyNailJustin said: 14 bolt uses "thick" ring gear no new carrier. . AXLE IDENTIFICATION Chevrolet began the manufacture of their own design Front Drive Axles for use on 1/ 2 . 4. SKU: GM10-410DC. Installation. For simplicity, I generally calculate at 60 mph - here's how the tire size/gearing/rpm formula pencils out for my current set up, and for the ratio changes I'm considering.. Current setup - 3.73 diff ratio: 813 (tire revs per mile) x 3.73 (diff ratio) = 3032 (driveshaft rpm) x .67 (4th gear OD ratio) = 2031 rpm @ 60 mph. Has a 10 bolt cover as well as 10 bolts securing the ring gear. 1967-1969 Camaro Manual Transmission Castings; Transmission Case Info 1967 1968 1969; Saginaw 3-speed: . While for the most part this is true, there is one exception—the GM 8.5-inch ring-gear 10-bolt. In 1971, GM instituted a standardized "corporate" rear axle. Read the metal tag attached to one of the differential cover bolts. The non C-clip 8.5" 10 bolt, type "C" rearend was used in some 1969-'72 Pontiac GP and 1970-'72 Monte Carlo. Like all Chevy 10-bolts, the axles are retained by C-clips on the inner end of the axle shaft inside the carrier. CHEVROLET 12-BOLT PASSENGER CAR Ring and Pinion Sets We offer complete coverage of ratios for your 12-bolt rears. USA Standard Master Overhaul kit for the '64-'72 GM 8.2" 10-bolt. Proper identification will be necessary for the purpose of ordering parts. The 12-bolt was used in many vehicles . Product Description; Additional Information; Product Description. All possible differential ratios above 2.73:1 can be swapped without having to change carriers (except for the . The truth is the 8.5-inch 10-bolt is almost as strong as a 12-bolt since its ring-gear diameter is . Aftermarket GM 10 bolt 8.2 gears are made to be stronger than OEM gears. Axle Type. All Yukon Gear GM 10 bolt 8.5 inch ring and pinion gears are manufactured to the highest specifications. Transaxle. That being said, limited gear sets are offered for the carriers, especially if you plan to change gear ratios. Popular OEM and Aftermarket Gear Ratios. Information about Differentials in GM vehicles can usually be obtained by looking at the RPO or "Regular Production . The 10-bolt was used in all the low performance applications. The GM 7.625" version of the axle uses a slightly larger 7.625" diameter ring gear with 28 spline axle shafts, however, because both models use the same axle housing, the . Dana catalogue page on GM 14 bolt (10.5") West Coast Differentials Catalogue page on the GM 14bolt (10.5") GM 14 Bolt Specs . Differential Identification. My rear is the bolt in axles. 1967 Model ID: Numbers Decode: General Info: Interior: Transmission: 1968 Model ID: Drivetrain Decode: Options: Underhood: . GM 10.5" 14-Bolt: 4.10:1 and down 4.165" deck height: 4.56:1 and up 4.520" deck height: GM 7.5" 3.08:1 and down, 2-series, 1.660 . Carefully count the number of full revolutions the driveshaft makes. 8.875 Ring Gear Diameter 30 Spline Pinion 1-1/8" Pinion Nut Ring Gear Bolt: 9/16" Head, 3/8"-24 R.H. RC12-3.42 RC12-3.55 . Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled "Service Parts Identification" inside the drivers door panel or glove box. F17. Typically, 10-bolt carriers are specific to a series of gears. _____ M.P.H. Ring and Pinion Installation Kit, Bearings and Shims, 8.2 in. Our experts will help you find the correct ring and pinion set for your particular application. Teeth: 39-10. Item #: GM8.5-373-YG Yukon Gear. Ring Gear Dia. The 10 bolt Chevelle rear end has the 8.2" ring gear from 1964 to early 1972. If unknown, please consult your local mechanic as these items are critical to selecting the appropriate differential unit. F16. Count the number of bolts that secure the differential cover. The following is a complete list of GM RPO axle codes for Chevy and GMC vehicles starting with the letter F. RPO. 8 specifications: • rg diameter 8.875" • 8 7/16" x 20 rh threaded bolts • pinion diameter 1.625" 28 splines • cases:2.73 & numerically lower GM Axle Types. Give us a call at 800-216-1632 to get started. . Vehicle data shows axle is a 12 bolt, GM references indicate 10 bolt. you will be able to learn alot about the rear differential in your classic full size Chevy. GM 4.10:1 ring gear . Jan 6, 2009. USD 327.94 327.94 1 327.94. Change the gear ratio of your GM car with these 7.5" 10 bolt gear sets. (Accurate identification using the GM RPO code assumes that the rear end has not been previously modified) The prefix is usually F, G or H when referring to . My Account: 0 item(s) View Cart: Home: My Account: . CASE, Diff. 2.53. Dana Dana 30 - Standard, Reverse Rotation, CS & TJ Dana 30 - JK Ring Gear Diameter: 7.20" / 181mm Ring Gear Diameter: 7.33" / 186mm . Several differential carriers are offered for the 10-bolt axle assemblies. Only show this user. But the 8.5-inch 10-bolt is actually just as strong as a 12-bolt or Ford 9-inch rear, with only a fraction of an inch difference in the ring gear diameter. Product Summary. GM RPO Codes - Factory Identification Labels and Interpretation. To improve the strength of the 10-bolt would be to upgrade the axles, and the ring gear. Only show this user. However, determining the different gear ratios of the . . The1971-'72 Buick GS/Skylark and Olds Cutlass A-body 8.5 10 bolt did not have C-clip axles. Likewise, ring gear thickness must increase to properly mate to the smaller diameter pinion. I agree, pull the 10 bolts, then look on the ring gear, 2 numbers will be stamped on it, example 12 - 44 Divide them, that will give you your ratio. Chevy 12 Bolt Gear Ratios - 17 images - gm 12 bolt chevrolet car kit posi unit gear, gm 10 bolt rebuild, history and identification of chevy 10 and 12 bolt chevy, motive gear performance big ten brand performance axle, My current setup is as follows: 86 K-5/350/700R/ 4:88's/ 10 bolts. Learn More. i just talked with dunks performance out of springfield oregon. The1971-'72 Buick GS/Skylark and Olds Cutlass A-body 8.5 10 bolt did not have C-clip axles. A shift number (1 or 2) along with a letter for the Positraction manufacturer (when applicable). Jeff Smith: When Chevrolet built the first Camaros in 1967, they were already in production of both 10- and 12-bolt rear-end housings. ZG GM8.2-355 . 800-646-6718 . Compared to the 14-bolt full-float axle, the 14 bolt semi-float has a smaller ring gear (9.5″), and the axle shaft can not be removed without also removing the wheels. USD 327.94 327.94 1 327.94. Hanging 12. 41 teeth on ring gear: 41 teeth on ring gear: 40 teeth on ring gear: 10 teeth on pinion: 12 teeth on pinion: 13 teeth on pinion: 41/10 = 4.10: 41 . Menu. 1967 rear spring mounting pads had a raised 'hat' design and tapered coil . Transaxle. There were two 8.5-inch carriers used: one for 3.23:1 and lower ratios, and one for 3.43:1 and higher ratios. Gear Calculatoris available on RICHMOND website www.richmondgear.com The following formula has been developed to calculate the optimum final Gear Ratio to suit your application. Ratio. Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled "Service Parts Identification" inside . 1958-1970 Chevy Rear Differential code Identification : . Estimated to ship direct from manufacturer on 06/13/22, pending manufacturer availability. D = Day shift N = Night shift 1 = Day shift 2 = Night shift - = No positraction D = Dana . 40 5531 2402525 10 BOLT, Gear to Case (Also Part of Gear Kit 5.529) 41 5.510 . You can typically find your RPO code on driver side door panel or glove box. I`ve seen guys take the cover off and see 41 - 11 stamped on the ring gear and they`ll say "hey,, some 4.11`s!" and i do believe 41 - 11 is 3.73`s. The GM 7.5" 10 Bolt axle, also known as the AAM 7.5", GM 7.6", and GM 7.625" axle is the most common housing used in GM G-body car vehicles and features a 7.5" diameter ring . These ring and pinion sets are manufactured to meet exact specifications to ensure a quality product every time. J.T. The following gears fit all GM 10.5" 14 bolt axles that have been shaved for improved ground clearance: Part Number Gear Ratio Rotation Carrier Notes Pricing; CRG-GM105-373-S: 3.73: Standard: 4.10 & Down: Shaved 10.05" Ring Gear: Check Price: CRG-GM105-410-S: 4.10: Standard: 4.10 & Down: Individual gear ratio identification codes can be found for their respective years on this website. Differentials that feature Positraction will have a small identification number comprising two or three digits, located on the lower right side of the . The 8.5-inch 10-bolt was used in cars and trucks over a wide range of years. Typically, 10-bolt differentials are specific to a series of gears. 10-Bolt Carriers. All of which can have different gear ratios. . Sometimes referred to as the "corporate 10-bolt", the GM 8.5" 10-bolt rearend began production in 1971 to replace the 8.2" and 12-bolt rearends. Qty: Add to Cart. General Motors rear end differentials are referred to by the diameter of the ring gear, i.e. Email to a Friend. The pinion nut will be 1 1/4". Drivetrain Partial VIN's The partial VIN, . Description. The first letter of the part number indicates manufacturer. . 10.50 5.13 RATIO THICK GEAR 4.10 &DN CARRIER: MOTIVE GEAR: MG3663696GM . count and gear ratio. 1967 Camaro Rear Axle Identification. Richmond Gear GM Ring & Pinion Gear Set Ratio: 3.90. Save. Apr 13, 2016. GM, 10-Bolt, Kit. Home > GM 8.6" 10 Bolt : GM 8.6" 10 Bolt: GM 8.6" Rear, 1999 and newer Trucks. Exclusive 9" Gear Ratios-----Ford. All corporate 8.5" 10-bolts have a 30-spline pinion, but various years & styles had C-clips or bolt-in axles. Find the Eaton differential . I agree, pull the 10 bolts, then look on the ring gear, 2 numbers will be stamped on it, example 12 - 44 Divide them, that will give you your ratio. The pinion diameter is 1.438 inches, and has 25 splines. at CA, KY, MN, WA. Item #: GM8.5-373-YG Yukon Gear. It wasn't until late 1972 that the 10 bolt 8.5" ring gear was used in Chevelles. If you intend to install these ratios with a "2 . Millions of Chevrolet vehicles were built and sold in the 1960s and 1970s, and the great majority of those were rear-wheel-drive models with differentials known as 10-bolts or 12-bolts. Remember, the actual rpm indicated in the chart will be slightly higher (between 100 and 300 rpm) on vehicles equipped with an automatic transmission. The GM 10 Bolt 7.5 rear end, also known as the AAM 7.5, GM 7.6, and GM 7.625 rear end was the most common housing used in GM G-body car vehicles. The quotient will be the gear ratio to :1. Dana Dana 30 - Standard, Reverse Rotation, CS & TJ Dana 30 - JK Ring Gear Diameter: 7.20" / 181mm Ring Gear Diameter: 7.33" / 186mm . Also with a new master rebuild kit, which comes with Timken bearings, will ensure greater strength and durability. 1971 - 1989 GM 10 bolt C-Clip 8.5" 1.20" 28 2.73 & up 187C149A* A556*91219557-010* 1964 - 1971 GM 10 bolt Buick, 8.2" 1.25" 28 3.36 & up 19674-010 Olds and Pontiac . GM 8.5" -1968-70 Oldsmobile 12-Bolt Cover/10-Bolt Gear GM 8.6" - 2000 & Newer 1/2 Ton Truck Ring Gear Diameter: 8.5" Ring Gear Diameter: 8.6" . Step 1. Cast Aluminum T-10 GM bell housing bolt pattern Passenger side casting numbers T10D-1 (B) 2 (19) 62 (R) Stamped side flange WL22-3 128940 Stamped top flange 56 Tailshaft casting T10-7D 940 R-1 3813490 9-11-62 . The result is your gear ratio. A Series 2 carrier will work with 2.56 and higher gears (numerically lower) such as 2.41. In 1970 the rear end was built in both 10 and 12 bolt versions. As the name implies, GM 10-bolt differentials will utilize 10 bolts to secure the differential cover to the carrier. If the vehicle was purchased secondhand, this tag may not be valid if . Still, the 14-bolt semi-float is a solid axle for a . Full size Blazer, C10, K10 front starting in 1977, K1500 and K2500 Front IFS starting in 1988 . View Details. In other words, if the drive shaft turns 3 & 3/4 turns, you probably have a 3.73 gear ratio. There are several differentials for the 10-bolt rearend. This is your gear ratio. The 8.2 rear end has 3/8" ring gear bolts with 9/16" head where the 8.5 . 3-series is 3.08, 3.36 and 3.55 (other ratios available in aftermarket). This gives me a more accurate count. D = Day shift N = Night shift 1 = Day shift 2 = Night shift - = No positraction D = Dana . Original gear ratios range from 2.41:1 all the way up to 4.10:1 in some pickups. Some people will trash talk the GM 10-bolt as a "junk" rearend, and if they are talking about the 8.2-inch, then they are not far off. The non C-clip 8.5" 10 bolt, type "C" rearend was used in some 1969-'72 Pontiac GP and 1970-'72 Monte Carlo. Call Sierra Gear & Axle at (800)792-2714. Ring Gear Diameter: 8.500 Cover Bolts: 10 Ring Gear Bolts: 10 Spline Count: 30 Dropout: False Pinion Support: False Carrier Breaks: 2.56 / 2.73 Rear Suspension: Solid : Featured Products RustyNailJustin said: 14 bolt uses "thick" ring gear no new carrier. ZK GM8.2 (37051) In Stock. A few use the 10 5/8" irregular cover. F17. Inside the 8.2-inch 10-bolt, the ring-gear bolts have 9/16-inch socket heads with 3/8-24 left-hand threads. High-performance limited-slip versions of these differentials also have been installed in Camaros, Chevelles, Corvettes, and many other GM muscle cars from 1964 through the 1970s, as well as Chevy and GMC . Transaxle. The code will tell you what was originally installed in the housing, but nothing about any changes that might have been made since then. 7.5 inch, 8.5 inch, 10.5 inch. Axle Type. We offer ring and pinion GM 10 Bolt 8.2 gears in all the ratios . Chevy 10-bolt car (8.2"): 2-series is 2.56 and 2.73. USA Standard Ring & Pinion gear set for GM 8.2" in a 3.55 ratio. Identify your GMC or Chevrolet rear end gear ratio by the RPO Codes, usually located on the placard labeled "Service Parts Identification" inside the drivers door panel or glove box. Raise and support the rear of the vehicle with jack stands. . GM RPO Codes, or General Motors "Regular Production Option" codes contain lots of valuable information about your GM vehicle. Yukon Gears are a high performance quiet gear, perfect for any GM 10 bolt 8.5" or 8.6" equip. A 2-Series carrier holds 2.56:1 and higher gears (numerically lower) such as 2.41. GM 10.5″ 14 . GM 8.5" -1968-70 Oldsmobile 12-Bolt Cover/10-Bolt Gear GM 8.6" - 2000 & Newer 1/2 Ton Truck Ring Gear Diameter: 8.5" Ring Gear Diameter: 8.6" . / Fill to Plug . 2.53. Has 10 bolt cover and 30 spline c/clip axles. 1965 - 1966 Mustang; 1967 - 1970 Mustang; Ratio: Plant: Day of Year: Shift: Posi Source: See Below: B = Buick C = Buffalo D = Cadillac G = Detroit Gear & Axle K = GM of Canada M = Pontiac/Canada O = Oldsmobile P = Pontiac W = Warren, MI: 001 = January 1st 002 = January 2nd 031 = January 31st etc. On some tags, the first 2 digits won't . However, only certain gear sets are offered for the carriers, especially if you change gear ratios. The GM 10.5" 14 Bolt axle, also known as the GM 14 Bolt and Corporate 14 Bolt has been in use by Chevy and GMC since 1973 and features . Much more accurate than trying to figure out what .36 revolutions is. Example: The ring gear has 41 teeth The pinion gear has 10 teeth 41----- = 4.10:1 gear ratio 10 Model Identification: General Motors utilizes differentials manufactured by several manufacturers. There have been non C-clip rearends found in Chevelle wagons, and some El Caminos through at least 1974. . Cover Bolt Count: 10: Ring gear Bolt count: 10: Ring Gear Bolt Size: 3/8 Fine Right Hand Thread (11/16 socket headed bolt) Axle Spline: 28 bolt in axle 60 degree spline: Yoke style U bolt & nut Universal joint retention (reference picture) Pinion Spline: 27: Carrier Ratio Breaks: 2.56-2.78 / 2.93-3.23 / 3.36- 4.33 and up: Pinion Diameter 1974 A and G Body Rear Axle ID : This chart applies to most GM 8.5 10-bolt axles . There was simultaneous use of the 8.2" and 8.5" rearends during the changeover period, like in the Nova. 3.23 and numerically higher ring & pinion ratios are designed for use with a "3 series" carrier. The gear ratio codes are located on the front passenger side of the differential as shown in the illustration below. All Yukon Gear GM 10 bolt 8.5 inch ring and pinion gears are manufactured to the highest specifications. I`ve seen guys take the cover off and see 41 - 11 stamped on the ring gear and they`ll say "hey,, some 4.11`s!" and i do believe 41 - 11 is 3.73`s. Semi-float 14-bolt axles are not quite as rugged as full-float 14 bolt axles. Large ID spindles; Common spindle nut threads with Dana60 front axle, meaning only one style of spindle nut and socket need be used / carried . The following is a complete list of GM RPO axle codes for Chevy and GMC vehicles starting with the letter F. RPO. We offer the most complete line of rear end parts for the GM 8.5" commonly referred to as the 10 Bolt differential, this differential was utilized GM used this very popular differential in there full size Chevrolets, Chevelle, Chevy II, Camaro and and GTO/Firebird Pontiac products starting in 1970. Rear spring mounting pads differed in that 1964-66 rear ends used a flat pad with a hole drilled in the center. F16. Just like a 10-bolt rearend, there should be stamped numbers on the axle tube - on the passenger's side. 10.5" 14 Bolt - Rear Axle; 11.5" 14 Bolt - Rear Axle; 11.5" Rear Axle; 12.0" Rear Axle; 195 MM Rear Axle; 218 MM Rear Axle; 250 MM Rear Axle . Ring Gear Bolt Torque: 120 ft-lbs Carrier Bearing Caps: 135 ft-lbs Gear Oil: Mineral Oil: Valvoline 80W-90: Full Synthetic: Mobil 1 75W-90: Recommended: Mobil 1 75W-140: Oil Capacity: 3.25 qt. Ratio: Plant: Day of Year: Shift: Posi Source: See Below: B = Buick C = Buffalo D = Cadillac G = Detroit Gear & Axle K = GM of Canada M = Pontiac/Canada O = Oldsmobile P = Pontiac W = Warren, MI: 001 = January 1st 002 = January 2nd 031 = January 31st etc. GM RPO Identification Codes. I mark the tire and the drive shaft and rotate the tires 10 revolutions. $204.99. GM 8.2 10 Bolt Differential Parts - Posi Units - Gears - Bearing Kits - 10 bolt cover with 8.2 ring gear. Traditional BOMs are 6 digits followed by 1 or 2 digits, and start with the numbers 60 or 61. Ratio: 3.90. Example. This assembly used an 8.2-inch ring gear diameter and 28-spline axles for Camaros, Chevelles, Impalas and even the early Chevy II's. There have been non C-clip rearends found in Chevelle wagons, and some El Caminos through at least 1974. Basic identification is simple. The ratio code is usually two letters (sometimes 3, sometimes a number & 2 letters), and is found on the right-hand axle tube. 1 - 12 of 12 Posts. Most 8.5" 10-bolts have a bulged-out 11" cover (for ring gear clearance) with big square lugs on the housing below the cover (red arrows).