Wheel hop. 68 383 4 spd

All of the above suggestions that it's time for new springs are spot-on. I just wanted to add a little information regarding the snubber itself. I'm sure you've seen people say "take that off and throw it away" or "you'd be better off losing that 5 pounds"...... Most snubbers are used incorrectly, and are of very little use to a guy with a street car anyway. In order for the snubber to be of any use, it has to be up against or very, very close to the floorboard of the car. That's not good for a street car, no doubt. MaMopar actually called for the Max Wedge cars, which were really designed for competition straight line acceleration, to run the snubber against the floorboard.
I am firmly in the "pinion snubbers are worthless, throw them away" camp. As said above, unless a snubber is against, or at least VERY close to the floor, it CANT do anything.
If it's against the floor, every bump you hit the snubber makes the ride solid, no suspension, no spring, and beats up the floor of the car. Not good. If it DOESNT contact the floor, how can it DO anything?
If i had one on my car (I certainly dont!) It would do absolutely nothing even if it were against the floor, because on a full power launch, the body of the car raises at least three to four inches (used to be six!) So the glorious wonderful pinion snubber is waving in the breeze, a quarter of a foot away from doing ANYTHING.

Sorry for the rant, I guess I don't think much of pinion snubbers.......