I am, but my car has a B-body rear,which gives me an extra inch of BS over a E-body. I tried a 5 1/4 BS first, which left me with a half inch to the lip (unrolled). I switched to a 5 3/4in BS (both on a 10 inch rim) and it gave me the clearance I was looking for at the outer lip. _However, my BS is so tight I will HAVE to run a 1 inch relocation kit from Doctor Diff to ensure no leaf spring rubbing.