C2 Differential identification for ordering parts

[Steve D.]

I want to order a rear end rebuild kit, but am not sure how to specifically describe the unit for ordering parts. Is it sufficient to identify it as a mid-year Corvette? The car is 63, but the differential is not original. The ring gear has (I think) a 67 date reference (GM 10-67). The positrac unit appears to be an Eaton. Casting # on housing is GM 3899143 NF. Stamped # on edge next to spring mount 1AO1 5 68 W. Casting # on rear cover is 3871375. Casting # on the differential case is EDB 30117 2.

Steve

[Joe L.]

Re: C2 Differential identification for ordering pa

Steve-----

Most of the 63-79 differential parts are interchangeable. Notable exceptions are certain components for 63-65. From the description of the components that are part of your unit, I would say that it's a safe bet that you have the 67-79 style unit. So, if you order a kit for a 67-79 I think you'll have all of the correct parts. Whether or not you'll have all the parts you need I don't know. The kits usually contain normal replacement parts used at rebuild time. However, if you have worn parts which are not "normally" replaced, then you'll have to obtain them seperately.

[Craig S.]

Re: C2 Differential identification for ordering pa

Steve - you have a rear end out of a 68 in your 63. The EDB30117 casting is for a 3 series Eaton posi case. This will take the standard rebuild parts used for any 64-79 rear end. DTS (Drive Train Specialties) carries the Eaton posi packs you need, and I am sure will have the bearings etc, but I usually buy them locally at a Timken bearing jobber as they cost far less than if you go to auto retailers. As far as setup of the rear, usually the shimming in place will be very close or exact after new bearings are installed, and generally the posi packs have a 0.030" shim behind each pack in the posi-case. The pinion shim is generally 0.029-0.031" behind the pinion, and I would use the same shim in place after replacing the bearings. Use a new crush sleeve, and check the condition of the side yoke ends for wear and damage, as they will affect end play of the completed posi/side yoke unit. Craig

[Steve D.]

Re: C2 Differential identification for ordering pa

Where can the crush sleeve and pinion nut be acquired separately (i.e. if not in a kit)? GM dealer?

Steve

[Joe L.]

Re: C2 Differential identification for ordering pa

Steve----

spacer ("crush sleeve")= GM #3954483----$8.31 GM list/each

pinion nut= GM #3752901------$6.38 GM list/each

[Steve D.]

Thank you. *NM*