Found a 8 3/4,but have a question

I didn't think they even did 8.75 in F bodies, but I did have an 8.25 from an F body in my 67 Dart when I bought it. The perches are just a hair under 44.5" inches center to center, so you would need to move them in. Also, they use a leaf spring isolator setup with giant holes in the perches, but if you just get new perches when you move then you should be fine. From what I've measured an F body rear is almost the exact same as a B body size-wise. Since I didn't put it in the car I can't really say much else, but it seemed to fit fine when I bought it.