I am looking for some backing plates to fit my 12 Bolt rear going into my 69 Chevelle. I am wondering if a set out of a 77 or newer caprice with the 8.5 rear or the maybe the 7.5 rears in the 78- newer montes and such. Are either of these useable in my application. I would like to use my original drums and such if possible.

What happened to the original backing plates? If you had a 10 bolt in there and are now dropping in a 12 bolt the backing plates will interchange between the two just clean em up and put them on. ;)