part ID help??

[Steve G.]

Hello-
A couple of us were looking at a part, best described as the "differential front bracket" : it bolts to the front part of the differential with 2 long bolts. We had 2... one had a reinforcement welded across the section where the 2 long bolts went through, the other did not. Pictures and drawings in Noland Adams book seem to suggest the bracket without the welded reinforcement were for 63-67, making it seem the other was for 68-79.
Is this true? Any help???

I have a picture of this part, email me at sgvette@aol.com if you want to see it. Thanks.

[Joe L.]

Re: part ID help??

Steve------

There were several different "snubber" brackets used over the 63-79 period. The first one was GM #3820186. I don't think that this one had any reinforcements welded to the cross bolt holes. It was used for 1963.

The second was GM #3843683. As far as I know, it was configured pretty much like the 3820186. I don't think that it had any reinforcments welded to the cross bolt holes, but I'm not 100% sure about this. This was used for the 1964 model year and, possibly, very early 1965.

The third was GM #3868799. This one had a round reinforcement ("thick washer") welded to the FORWARD cross bolt holes on either side. It was used for 1965-1968.

The last was GM #3921657. This is the one that has the rectangular, reinforcing "plates" welded to each side of the bracket and through which the cross bolts pass. This mount was used from 1969 through 1979. It may also have been used for later 1968, as well.

[Steve G.]

Re: part ID help??

Very helpful answer. Thanks a lot, Joe.

[Wayne M.]

A bit of the story on C2 front diff brackets

The auto-load pic shows mod's to correct/prevent elongation of front diff brkt holes. Link at bottom of pic is for 1st page of Tech Service bulletin. It calls out the same part #'s you have listed. I notice in my '65 AIM that prior to 7-9-64 the bracket # was 3843683.

Another way to tell the latter C3? diff brackets is the absence of a "lip" on the forward-most part of the tongue (mounts to frame).

RHS of page shows how early '65 and prior differential cases (3818753-N, with THREADED forward bracket mount holes) were corrected.