Converting rear 9.5 rear brakes to 11 inch drum brakes

[Lynn]

Have a thread going for my El Camino that I use to tow.

Here: https://www.yenko.net/forum/showthrea...19#post1352619

I picked up a good 3.31 12 bolt. Before swapping it in, I wanted to install 11 inch drums on the rear. Bought some 11 inch backing plates on ebay that were advertised to work with any "C" clip 12 bolt. Not so much.

Pics attached.

Can anyone tell me what model 12 bolts used 11 inch rear drums? I am guessing all the 60's V8 full size cars got 12 bolts, and all wagons, everything with a big block or HD brakes got 11 inch rear brakes.

Any guidance on what will bolt on? Please don't suggest rear discs. i really just want to go 11 inch drums if at all possible.