[joyridin']

I believe the length of the arms are the same, but they moved the spring perches rearward on the later Mustangs. Your best bet is to get a set of aftermarket upper and lower control arms and modify the spring perch on the lower arm. I grabbed a set of Factory 5 tubular arms, removed the perch, and welded it in the correct spot. It worked fine. Also, it looks as though you are using the spring from a later Mustang. You would have to shorten the spring or find a shorter one from a Mustang 2. I do not think you can remove the upper mount and move it back as it will hit the body. You would have to cut holes in the trunk.

The easiest fix if you can do it is find a set of QA1 coilovers from a Mustang and mount them on the rear. Then you can remove the upper spring perch altogether. They are relatively easy to find.