B-body 83/4 into a A-body

I have a '68-70 B body rear in my Duster. The perches need to be moved to do it right. You can side load the springs enough to make it work, but make no illusions about that being the right way to do it. Yes, it can and has been done, no, it isn't how it should be done.

B-body perches are at 44" c-c, A body perches are at 43" c-c. If you slot the perches and pull the springs you're side loading the springs and losing tire clearance. The A and B body perches are also not welded at the same angle from the factory, although that can be corrected with shims, and the factory angle might not be right for your car anyway depending on its ride height etc.

Could you flip a set of 1/2" offset spring/shackle mounts side to side to make it work? Yes, but again, you're losing a 1/2" spring clearance if you do that. Moving the perches isn't that hard, and it shouldn't be all that expensive if you need to pay someone to do it. Plus, if you're moving the perches, you can install that 1/2" offset spring kit correctly and gain a 1/2" of spring clearance at the same time instead of losing it.