I recently purchased a cool 51 Chevy, not from the original builder, and was told it has an older camaro subframe. It is definitely a GM product and has the steering box in front of the cross member. The ends of the subframe were cut off when grafted on. I've read on another forum that the id numbers were on the back end of the subframe. I also read on a forum that the numbers stamped on top of the upper control arms would identify the year of the build. The numbers on the left upper control arm are 05B8L. Numbers on the right arm are J26B8A. I believe its a 70-81 subframe but haven't yet been able to verify. Any help is appreciated.
Newby to forum.

 

I've just posted a thread asking a similar question as to the front control arms. if the steering box is in front of the crossmember, I've been told that's a 1970-1981 subframe. if you happen to locate a website or answer to your question, please pass it along. thanks