i'm not sure, but i thought i had read somewhere, that these vans were based on a-body chassis. as stated the spring perches are mounted on top of the housing. i would check the width, let us know if its right.
mike ..i think you may be correct, i am not sure but i think i used a van rear in a dart a few years back, cant say for sure it may be the same as a b- body
either way it did fit , i just dont remember how well.....