Question after converting a 7-1/4 to 8-3/4

19 Again.. said
Yes it has 10-1/2 drums, but you made me go out and measure the studs on the 8-3/4.. If I read the tape measure right it appears the studs are at a 4" bolt pattern. In which case I'll have to have the axles re-drilled for a 4-1/2 pattern which is on the car right now with the 7-1/4. Something of which I had forgotten. Just one more thing to add to the list. Glad I looked before I got into it.. Looking at the backing plate on the 7-1/4 it looks Identical to the 8-3/4.. But the floor is pretty cold and I'm not as young as I used to be so I didn't slide underneath the car to verify the backing plate bolts. LOL!!!

If it's a stock A-body 8 3/4, it would have 10 X 1 3/4" brakes and the small bolt pattern. Those backing plates won't work with 2 1/2" shoes so you'll have to use the correct ones that match the 2 1/2" shoes. I'm not sure if you can use those ones off the 7 1/4 or not. It seems to me I remember something about the distance from the end of the housing to the end of the axle shaft was different on those two applications. Maybe someone that has acually done this particular swap will chime in here to verify or tell me I'm full of it.