I have a Bbody rear end in my 72 dart, I put it in more than 20 years ago. When I installed it, I just pulled the springs apart to fit the perch width. Over time both mounting brackets for the spring shackles were twisted, and actually started to separate from the frame. I have since realigned, and reinforced the shackle mounting brackets. I also moved the perches in on the rear end to A body specs. Not saying anyone is wrong, just saying what happened to my car when I inadvertently put too much stress on the shackle mounts.
