Thread: 1957-61 chevy 10 bolt

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I have a 57-61 chevy 10 bolt rear. It has 3725899 casting number and BB stamped on one of the axle tubes. I have it in my 23 T Bucket. I want to convert it to disc brakes and change the gear and carrier to a LSD. Can anyone point me in the right direction? I cannot find much info out on it, like is it a 8.5" rear, what spline, etc. Thanks.

Check Jegs, they list both the disc brake conversion and New Posi units. If you have questions call their tech line, of the manufactures tech line. Worst case you might have to pull a rear axle to verify spline count .....but I think the splines were the same from 55-64.


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It may not be the way you want to go, but these guys put together complete kits that ensure that all the parts work together, and they'll put together what you want, like just a kit for the rear if you call them - Chevrolet Impala Disc Brakes

For the differential, I needed a complete third member, so I called the guys at "Just Rear Ends" - Just Rear End's Complete Custom Crate Rear End, Ford 8 Inch and 9 Inch Third Member, Chevy 12 Bolt, Posi, Housings, Axles, Wilwood Disk Brakes A father/son team who specialize in differentials, and do them right - just not sure they do the older Chevy third members. There's others out there too, like Yukon Gear & Axle, but I like the small, family run shops when I can find them. I'm pretty sure that all of the '57-'64's were 17 spline, 8.4" ring gear.

I really want to try to keep what I have. All the bracket are in place and I really don't have 3K to put into the rear. Just found out the motor is about 4500.00 and with everything else, Im approaching budget quickly.

I have used the weld on brackets from Speedway with good success, until several years ago thats about the only option you had, uses the standard metric calipers that are cheap and reliable and the brackets are universal that fit 3" tubes I believe.

For your differential, look around for a local 4X4 shop that services the off-road crowd. If they truly support the off-roader's then they will be well versed on swapping out ring & pinion, and also dropping in a posi-trac. I'd strongly recommend that you consider something like an Eaton/Detroit Tru-Track spiral gear locker, which is very, very street friendly, locks solid, and is all but bullet proof.

I would like to put a true track in it. The first thing I need is to identify the rear end. I cannot find anything on what size rear(8.2 or 8.5) what spline axles etc. Cannot find anything that goes back that far. It also has the removable carrier( dumps out like a ford 9")

1958-1970 Full size rear Differential Identification you should find what you need here

The '55 to '64 rear gears are 8.4", 17 spline axles, and with what Charlie posted the BB means you've very likely got 3.36 to one gears. Here's Yukon's link to verify - https://www.yukongear.com/diffdetail...fName%3DGM+55P

rspears thats the info I was looking for. Thanks. Now just need to find the carrier I need and maybe change the ring and pinion to 355-373. Oh and also find the rear disc conversion

The tracloc is a carrier

Thats what I meant the trac loc or true loc. Just need to find the carrier I want.

Found a Auburn carrier for it (5420100). Now to take everything apart. Only thing is, I have never done it. Can anyone give and advice? I looked on youtube and couldn't find anything like what I have. everything was 1964 up. With it being a 57-61 and dumps out the front I know its different than the rear dump.

If you have never done it-don't try------take your housing to someone who does it often------ you won't need a carrier--------the new one(trac loc?) will be different than the one you have , but you will need one that fits the range of ratios that your looking to get-------GM was that way while Ford just used different thickness of ring gears-----

Originally Posted by sefrayser

Found a Auburn carrier for it (5420100). Now to take everything apart. Only thing is, I have never done it. Can anyone give and advice? I looked on youtube and couldn't find anything like what I have. everything was 1964 up. With it being a 57-61 and dumps out the front I know its different than the rear dump.

Everything from '57 to '64 was the same design. There was no cutoff at '61 with a big design change. Your differential has a third member that drops out the front after the axles are pulled, exactly like the '64 does. Once you get the third member out you'd be well advised to leave any further disassembly to someone who's done it before, and who will be putting the new stuff in. Like Jerry says, you don't need to buy a carrier if you're switching to a trac-loc or tru-trac, or any other kind of posi-trac unit. Those ARE the carrier, so you'll be wasting your time and money on the Auburn.