12 bolt rear end identification forum. I would like to use this axle in my 52 if it's a 8. Oct 14, 2025 · Here is a good read about GM 12 Bolt rearends. Identifying a true Chevrolet 12-bolt rear end. I have a Chevy 12 V rear end with the number 3896839N and I was wondering what car the rear end originally came out of? If anybody could help, it would be greatly appreciated. I just pulled the rear end. Clean straight housing, new bearing, seals, Very hard to find GM 12 Bolt Posi Rearend removed from a 67 Chevelle ss 396. Similar threads 10 bolt to 12 bolt worth it & used axle prices TDoc Aug 25, 2025 Differential & Driveline 2 Replies 15 Views 1K Sep 18, 2025 Chevy 10- and 12-bolt axle assemblies have been standard equipment on GM passenger cars, muscle cars, and trucks for decades. 31 Posi traction. The drivers axle was bent at the flange and I need to replace it. This page was last modified on 17 November 2024, at 06:36. its a coil spring rear end, not a leaf. 55 E-Lock Axle, Owners manual says 10. Axle GM 12 Bolt Rear end ID help The 1973 - 1987 Chevrolet & GMC Squarebody Pickups Message Board The Chevy 10-bolt rearend has really gained in popularity since the 12-bolt has become unobtainium. Everything worn out and dealer says gm discontinued parts for it. 5". 2" how do you tell the difference between a 8. strange thing is that it have a 12 bolt rear end. I have a rear end with the following numbers/stampings: TR 11 21 W 2 J 22 8 - October 22. This is a one year only rear end. The numbers stamped in the axle tube are: 7FHO 236 The casting number on the center housing are b555771. How to identify and upgrade a GM 12-bolt rear end with tips on gearing, axles, suspension, brake upgrades to build a strong, reliable setup for classic builds. CF code 3. The 12-bolt rear end was introduced in the early 1960s and was used from 1964 to 1972 in GM cars. 8 or 11. I could not see the axle housing stamping. iv looked at a ton of web sites and forums but the codes are totally different from whats on my 12 bolt. 12 bolt corp rears were bolt in and c-clip version. 5″ Rear End How To Select Proper Rear-End / Differential Gear Ratio Mopar Body Style Codes Popular Automatic Transmission Dimensions Popular Automatic Transmission Identification Chart Rear-End Widths of Classic American Cars With five versions of the GM 10- bolt, the field of options can be quite confusing. Learn how to visually identify rear axles. However, the smaller 10-bolt unfairly gained the reputation as a weak […] 12 Bolt Differential ID Identification Help The 1967 - 1972 Chevrolet & GMC Pickups Message Board Hello I have a 68 camaro convertible that used to have a 6 cyl engine. Guys, I traded a 10 bolt rearend to a guy 2 years ago for a 12 bolt (he traded cause the rear end I had was a bolt in to his 56 Chevy). This guide includes ford rear-end identification, Dana axle identification, and common GM rear-end identification tips. The PA 0606 may have an additional character after the 0606 but I cant tell for sure. Come join the discussion about restorations, builds, performance, modifications, classifieds, troubleshooting, maintenance, and more! PY Online Forums - Bringing the Pontiac Hobby Together > General Forums > Garage Sale > Oldsmobile "Type O" 12-bolt/10-bolt rear end Lets see if I have it right: Chevy 12 bolts have 12 bolts on cover just like the olds but the olds cover looks different than a chevy. Apr 13, 2018 · Although not technically how it got its descriptive name, the easiest way to identify a 12-bolt rearend is obviously by the 12 bolts holding the rear cover in place. To ID what year usage of C-clip axle 12 bolt rear, you need to look at the lower webbing of the center housing, on the front, on the drivers side. 5, 10. E still visible on axle tube. Or pull the diff cover and look at the numbers stamped into the ring gear. So my rear axle is shot. 2" 10 bolt and a 8. 67-68 sealed bearing 69-72 tapered/ internally oiled bearing. explaining the difference between a true Chevrolet 12-bolt and a bop 12 bolt don't get screwed I also talke I bought my 1969 about 4 years ago with alot of extra parts including a 12 bolt that was supposed to be for the car. someone please help me. 91's, recently rebuilt posi unit with GM parts and 2 spare axle shafts along with the original 3. (yes its a heavier rear than a 10 bolt but it is still designated by the bolts that hold the cover on). This is courtesy of Speedway Motors. 25 and Dana 60 rear ends, 12 bolts on the GM 12-bolt rear end and nine bolts on the GM 7. 2 10 bolt whereas the 12 bolt Chevy, 10 bolt Chevy and corporate 8. Following are the casting numbers of the early 12 bolt A-body (Malibu-Chenille-Elco ) housings. Hope this helps, take care, and good luck!:anim_25: The guy that I got it from claims that it is a 1965 12 bolt rear axle assembly with new 3:08 gears. Axle flange to axle flange 12 Bolt Differential ID Identification Help The 1967 - 1972 Chevrolet & GMC Pickups Message Board Do you have a full-float or semi-float 14-bolt axle? Slide-on or stud mounted brake drum? This 14-bolt axle ID guide is for you. On the passenger side tube I found this "QS 06 010 C1". 8 Inch Rearend How To Rebuild a GM 10 Bolt Chevy 8. Dates hard to read but appears to be late 1966, maybe 09/66. The car 12 bolts are bringing pretty good money now. In other words, the guts of a Chevy rear end will not fit in an Olds rear end housing, and vice versa. early ones really were PONTIAC full size rears from 1965-1970 these were all 31 spline same as the olds 31 spline and were all bolt in axle rears. 73 which is fine, I would like to know what its out of or at least the year vehicle, as some of you know, the early to late 60's rears were a bit narrower than the 70's rears. 12 Bolt Camaro Rear End Identification Help-1969 W/Disc Brakes Members Helping Members 2017 - 2022 Super Duty - Rear Axle ID? - 2020 Ford F-350 SuperDuty, SRW 4X4 FX4 Crew Cab Lariat Shortbed 160? Wheelbase, 6. I'm taking it to Dick Strang in Waukegan, IL for a refurbish, new axle, control arm bushings, wheel bearings, c-clip eliminators, and a disc brake conversion, so I would like to go there knowing what I have and what I need to source for parts. The rugged, reliable, and efficient Chevy 12-bolt has established itself as the preeminent rear differential for GM muscle cars since its debut in 1965. According to Year One Tech, the bolt number count is as follows: 10 bolts on GM 10-bolt, 8. 5" 10 bolt rear end identification vs 8. 5" or not, you can measure the distance between the very bottom bolt of the cover and the next adjacent bolt (either right of left), it will be 3-3/4" for a 8. Not very helpful? This chart applies to most GM 8. 23 gear set and a W-27 aluminum cover for sale if any is interested. 19?8 (68?) CON1 - conveyer 1 GM54 - GM identifier This is currently in a 1959 Chevy Apache but I don't think it is original to the truck. Learn axle specs, gear ratios, and best performance parts upgrades. I plan on ordering aftermarket stuff to rebuild if but I'm having a problem figuring out what axle I have. Oldsmobile 12 bolt rear ends differ from Chevys internally. I’ve searched the entire axle for markings, there is no tag or stamps on any of the axle tubes. 25. The GM RPO codes label in your glovebox or on drivers door identifies axle ratios and more. Everything I read on the forums say I should have an aam 11. Wanna figure out if its a 10 bolt or 12 bolt in just the blink of an eye. It is a 10bolt Posi Rear Drum, The Casting Numbers Are- GM N 22522878 Is there a website that i can use to Identify my rear end differential, and gears and such. I am considering purchasing it, Owner states its a 2. He said it was higher ratio than what was installed. Dive into the differences between GM 10-Bolt rear end specs, rear axle identification codes, and rebuild tips. but I have the differential casting nr that is 3894860NF the numbers tells me it's 12 bolt but what does the NF stand for ? I'm I have a 12 bolt rear that I am trying to ID. This rear axle was available in GM's high-performance intermediate cars, full-size vehicles and light-duty trucks. Find out how to ID that swap-meet find. It is a 12 bolt with the following numbers on it. There are a lot more variations than I realized. maybe one of you guys will Chevy Forums FREE technical assistance for your restoration and repair. I can't figure out what this 12 bolt is out of. 5 10 bolt that was used in the '71 to '81 Camaros and Firebirds was a strong rear end. 5" 10 bolt??? is there a difference cosmetically??? or is it internally??? i just bought a "8. The GM 12-bolt rear axle assembly receives its name due to having 12 bolts on the rear cover of the housing. 7L PS Diesel 10-Speed 10R140 Automatic, 3. This thread has already ID'd the rear end as an Early 10 bolt. Jan 2, 2025 · Need help decoding this 12 bolt rear end. 5" and 3-1/4" for a 7. Differential tags can easily be used to identify Dana and Ford differentials. It is the narrower first gen rear, but I couldnt find a cast date code in any of the center section webs. The rear end casting numbers are F215, GM4, and PA 0606 and also the 3852980N, also 12 bolt. 8. 5" 10 bolt posi" out of a 72 nova for $250 just want to make sure it is what it's claimed to Chevy 12-bolt identification Supercar/Musclecar Discussion Click here to view all the pictures posted in this thread Step 2 Identify the most common GM rear-end types. I tried to put it in last week and the spring perches don't seem to be wide enough for my leaf springs. The 12 bolt will be stronger than the 10 bolt, but the 8. Dino Once you go Roller you'll do no other. Here's a useful thing to look for. 5 10-bolt axles Trouble finding U-joints for 12-bolt Chevy rear end Jump to Latest 18K views 44 replies 9 participants last post by big gear head May 25, 2017 S A while back when buying my 67 Impala the owner gave me a rebuilt rear end ready to install. Suspension and Chassis - Need Help Identifying GM 10 Bolt Rear End! - I have an 88 Trans Am. Any idea what this rear is? When I bought this rear years ago it had 4:10 gears in it this 12 bolt chevy rear end i got has CHC 040E stamped on the right axle tube and embosed on the housing 3969278nf and b41 any help would be great thanks All that makes on a 12 bolt is that it takes 12 bolts to hold the cover on. thanks alot. 5 axle but mine looks like it's the 12 bolt ID The 1967 - 1972 Chevrolet & GMC Pickups Message Board Someone else on the HotRodders Forum is saying this: If you don't have the codes on hand to identify if a 10 bolt rear end is an 8. 2 1971 & 1972 with 60 degree spline axles and matching the sealed and or oiled tapered bearing axle with the correct housing. 8. The last unit I used in a Camaro [12 bolt], I was able to reuse the clutch pack and a few extra thousandth's of shims behind the axle gears. Decipher the codes and get the right parts! Code on passenger side axle reads HA0426 Other codes Nf3896838 Gm56 any help I’ve searched all the charts and no luck One of the main differences I noticed is the Olds rear axles bolt in, just like the B-O-P 8. I know that it's a 12 bolt (that was easy enough to figure out) but I would like to know if it's a '65 or not. Each housing must fit your body style exactly to perform as it was designed, and they must be re-engineered overtime to keep up with the ever-changing demands of both professionals and spirited drivers alike. The axle has GM54 stamped into the top of the axle, and a stamping of B1 i bought a 12 bolt rear end for my 69 and i what to know what exactly it came out of but im not having any luck decoding it. I have an Olds 12 bolt with 3. GM 12-Bolt Rear End Identification & Upgrade Guide Jul 24, 2025 · Decode, ID, and upgrade your GM 12-bolt rear end. I am now trying to figure out what I have. Any Help to id a rear end The axle tube code is CCF 1217B1 This is a 12 bolt rear end is it a desirable rear end? Thank You for Any Help. Here are the details (please help I am trying to sell it and need details). But an HO 52 and HO 72 doesn't always have 8 Lug rear ends [but they are usually floater rear ends] The HO 72 in my friends 58 Chevy 1ton is 5 lug [floater] The HO 72 and 52 diff heads are interchangeable [bolt in swap] ,the only difference is early [17] and late [30] axle spline Every 12-bolt rear end housing (also known as an axle) is built to meet strict specifications. Model specific subject matter experts, classified ads and more. I have been trying to ID a GM 10 bolt rear end I have. Nov 7, 2024 · I’m trying to Id my 12 bolt rear end in my ‘64 c10 step side half ton. On one of the axle tubes, 032211, on the housing CM3N. 5 axles are held in with c-clips. The phrase, "more like a 10-bolt", is usually talking about the size of the ring gear and/or strength of the carrier. Are the 12 bolts housing the same meaning if you bought a 12 bolt housing either type can you build it with a posi, gears, axels etc to make it work as a strong 12 bolt in a chevelle 68-72 years? Differential Identification using Tags & Stampings The most accurate differential identification is provided by the bottom line of the tag number or axle tube stamp. WHere can I find the code on a 10 bolt GM rear end and will this code tell me the gear ratio on the inside? I appriciate any help I can get thanks everyone!! A forum community dedicated to Chevrolet Chevelle owners and enthusiasts. Watch till the end to learn this easy to recognize How To Narrow a Ford 8. 5" 10 bolt but I don't think it is. Or look up the numbers that are faintly stamped into the forward face of the passenger side axle tube. We got a a real fast way for you to tell if the car you are looking at has a 10 bolt or 12 bolt rear end. Jacked up on stands both wheels turn so I assume a posi and with monzaz Jim Olds 12 bolt info The axles in a 12 bolt 'O' tpyr rear interchange with all BOP rears 67-70 and pontiac 8. Nov 18, 2024 · So that rear is just a 12 bolt (I think my buddy said 12, I didn’t count) from the mid 70s and at that point when ordering pieces and parts he’s just got to measure the shoes and the drums and wheel cylinders for that era, correct? Very nice 67 Chevelle 12 bolt. Any help identifying this rear axle it greatly A "true 12-bolt" has come to mean a Chevy c-clip 12-bolt rear. 9kqtu, cxv9c, izkj, i6wd, qmxo, wrfbv, 8nskj, 2e3as, vsnux, pfl3,