Help ID this GM rear end in my '57 Chevy 3100 truck...
 

Hello!

This is my first post, so Hello! from Monroe, CT.

Here's why I'm posting...

This summer, a '57 Chevy 3100 pickup followed me home. It's an older resto that's been worked a bit...400sbc, turbo 400, and a posi rear end. The work appears to be solid and well done.

Anyway, when I bought the truck, the brake pedal sank to the floor, so I pulled apart the brakes, and found that I need an old fashioned brake job, along with a wheel cyl on the pass side. The previous owner (PO), left out all of the self adjusting AND the e-brake hardware, including the strut arm, and I want an E-brake, so I have to find the parts. Here's where it gets interesting, and the reason for my post...

I CANNOT positively ID the rear end, and I have to in order to get the proper brake parts. Here's what I've got...

It's a 10 bolt posi GM rear with 2.73 rear end gears.

Posi clutch is 2 plates between the spider gears held apart by 4 springs

Part # on the gear is 3984825 41 15 (tooth count). There is NO mfg date

Ring gear bolt heads are 3/4"

Carrier # is 32267

Numbers stamped on the front of the pass side axle tube are: NT K 084E

Bolt pattern is 5 x 5

Brakes are 11" x 2"

Wheel cyl has 29471 cast into it

This was a coil spring/trailing arm rear end - top of rear has trailing arm lugs cast into it, and I can see where the bottom mounts were cut off
The driveshaft has 2 u-joint mounted in a coupling at the rear end side

I've been digging for hours, along with posting on the HAMB, and from what I can find, the rear might be from a 71 - 76 GM full size, specifically a full size Pontiac.

Can anyone ID this rear end for me?

Last question - anyone know a vendor who sells GM e-brake strut levers?


Thanks in advance...

Chris

Looks like a GM corporate 8.5 from a full size GM car. IF the posi has 4 springs then it's an after market Eaton that someone has installed.

Searched for images for an 8.5" GM corporate rear, and it does have the lugs at the lower corners like an 8.5. I'll check the pinion nut size tomorrow...if it's 1 1/4", that will ID it as an 8.5, at least according to what I've found online.

Anyway to date it?

What cars would have this rear end come in? I ordered brake shoes from a '76 Impala, and they matched what's in there now, but I don't know if there's any different between Chevy brakes and Buick/Olds/Pontiac brakes.

Thanks...

Chris

Should be a Casting # and Date code on the Webs where Center joins Axle tubes.
Also a stamped code on the right axle tube.

What he said. :cool: