bottoming out problem
 

I was lucky enough to find a 67 SS convertible for my wife on her birthday. It is a driver and not a show car. The major problem is while driving and hitting larger bumps or swells in the road it sounds like it is bottominig out on the rear end. I checked the shocks by pushing down on the rear end and it bounces back up and part way down as I understand is correct. It did not "rock". It has single leaf springs that "look" ok, is there a way to test them? Or is there something else I need to check? Thanks for any input.

does the car sit low in the back...

No, it doesn't sit low. I checked the rear wheel wells to see it there were any tire marks from the tires hitting the sides or top and it is clean with no rub marks at all. Thanks.