Does anyone know what the biggest size brakes were used on 8.75" equipped c-body cars??

Seen 11 X 3's on some Imperials.

I have a `66 300 in the yard with 11x3 on the rear.

to convert to 3" shoes does it just take the 11x3 drums or do you need specific(11x3) backing plates also?

You need the backing plates too.

thank you John

So are you saying an 11x3 backing plate is different from an 11x2.5 backing plate?

I'm interesting in knowing this also. I've got a couple of sets of those 11 by 2.5's running around with the 5 on 4 1/2 pattern and the 5 on 5 1/5 pattern that would fit 8 3/4's.

I've changed my 12 x 2.5 to 12 x 3's on my 9 3/4 8 lug single wheel rear.