Will the 11" backing plates from a 70 98 bolt to a 66 cutlass rear? Will any of the full size backing plates bolt up?

 

The popular swap used to be the 11" rear brakes from a 1973-77 A-body. The drums even have the correct 5 x 4.75" bolt pattern. Unfortunately those parts aren't as common as the were 20 years ago. You might also want to try the 11" backing plates from the 1977-90 B-body wagons.

 

Thanks for the reply Joe. Your right, the popular stuff is gone. You can buy everything new, but the backing plates. I have located a very nice set of backing plates for a 98 with 11" brakes . Too far to go look at them." Seller" doesnt seem to want to sell them . He wont measure the bolt flange spacing. Oh well