64 rear diff cover

[Gary R.]

Re: 64 rear diff cover

Hi Tim
I have seen a lot of things when these come in. One was cardboard, another was a fiber type material, and also there were O-rings.

Here is a 63 plug and posi tag





Here is a screw driver through a blown out bolt hole in a cover




Here someone welded a similar blow out. I had no idea how long it was done by the time I got in the diff. It didn't leak but I installed a new HD cover anyway.



Here is a 63-64 plug no washer



Here is a 63-4 & later



Here is the o-ring notice the undercut above the threads.

[Joe L.]

Re: 64 rear diff cover

Hi Gary,

There has to be a sealing washer, on mine I had to buy a repro washer that in no way seals. If you have seen the correct washer in your comings and goings post it's size and material so I know what the original looks like.

Timothy------


The 63-64 filler plug gasket was GM #3714775. It was made of leather and was 1" ID and 1-9/32" OD. It was about 3/32" to 1/8" thick. I have a bunch of the NOS original gaskets around here somewhere. I can't find them at the moment (too lazy) but I can confirm they are just as described.