The easiest brake upgrade 8 3/4

Here is a photo 8 3/4 A Body housing. I used 10x2 1/2 drums and backing plates from a 72 B Body. The axles are Yukon and have the B Body drum hub register(axle center) that is larger than the A.Take the Aftermarket axle you have and your A body drum and check to see if it fits over the drum register. If the "drum" hub is too small then you have the correct aftermarket axle to use the B Body brake parts.
I hope this helps only because the aftermarket axles were available with both sizes of drum registers.This will also determine the backing plate offset.I've had both but now I think the aftermarket has discontinued the A body style drum hub register.