there's a difference between the strut rod mounting brackets at the wheels. The left bearing assembly has been rebuilt and I'm pretty darn sure the right one is all original. This is on a '71 with the 270hp 350ci motor. I can't imagine GM would put different sized mounting brackets on each side, so...

Can anyone guess where that left one came from?
When I have done parts searching, I don't see anywhere that states different sizes. Is the left one from a different year?
Was the left made in China?
And most importantly, am I in trouble with respect to reliability, stability, performance, etc?

Thanks...

 

71,

Over the production history of the C2 and the C3 GM changed the design of the rear trailing arm support several times. From 1963-1964 there were two designs that I’m aware of. 3820648 was the first casting number that I’m aware of on this part. In later years there were other changes made to the supports.

Between 1973-1974 GM changed the supports again when they did this the casting number also changed. 3820643 would probably be cast on one from 1973 and 348103 was used on 1974 and newer cars. These changes would include the web lower and different sizes in the lower rounded area of the support.

The best thing to find is the casting date and the casting number. They will tell you exactly what year the support is from. Imported reproductions to my knowledge do not carry casting dates so they are easy top spot. The issue is trying to see these two numbers when the support is installed is kind of hard.

Here is a 348103



Here is a 63-64



You can see there is a difference between your left and right that is not shown in my pictures. I would have to guess the one you have is the 74 and newer design which just means somewhere someone replaced this on you car and the only thing at the time was the current GM service Replacement part.

Willcox Inc.

 

You should be fine. Only thing I see is that you need to put cotter pins through those castle nuts.

 

Wilcox: I'll check for stamp #'s. Thanks a bunch for the info!

Van: Performance and stability are my largest concerns. Another thing I forgot to mention is the new strut rods are pretty tight on the left side. Hopefully the rubbing on the edge of the bushing will not cause failure or squeeks. And thanks for the reminder. I haven't torqued anything down yet, so those pins will be in soon.

 

71 as Van Steel stated, you should not have any problems with this support. It was offered as a workable replacement for all years when GM changed the design. I'm not much on the poly suspension but the struts you have on the car are listed for 68-79 so there should not be any issues.

The supports on the lower picture are interesting. They are very early 1963 supports and if you look real close, one is missing the casting date. This is the first case of a support with no casting date I have ever seen. Interesting and that was why we took the picture. The car this is on now is being judged and we wanted proof in case it ever became a question. However, seeing this when installed is next to impossible.

Willcox