Backing plates

[Joker13]

What is the difference between A and B body backing plates? I was given a set of Bs for a rear I’m having built and didn’t know if I can use them on my A body. Does bolt pattern come into play with these? I don’t think it does but just want to make sure.

 

[Jimacuda]

The difference is in the offset of the backing plate.
And its pretty much 72 back stock A body backing plates are one offset and all the rest of the 65 up mopar are another.(mostly)
If your replacing axles w large bolt pattern then you can most likely use them.
If not your pretty much stuck with 10x1.75 rear brakes and small bolt pattern.