This is a timely thread for me. Just started driving my '65 Belvedere and I think I have problems. As I ease into the throttle on a roll, the car feels like it stops accelerating when I hit about 75% throttle. I thought it was just spinning the tires but I got under there today and found that it had broken the rubber snubber off of my Mancini pinion snubber and that the diff had hit the exhaust.

Now I'm wondering if what I was feeling is the diff jumping off the ground. The leafs are original, I think, I left them in because I liked the stance of the car. Would SS springs raise the rear of the car at the curb?