i'm getting some heavy vibration in the front end (maybe engine, trans wheels, don't know) at 45 and 65, and it seems to stop if I ease off the gas. Any Ideas?

 

Could be lots of things--Is there any chance you have used fix-a-flat on a tire? One car that I bought had a rhythmic vibration and I couldn't balance the one tire. Broke the tire down and there must have been a cup of that liquid in the tire.

 

try ball joints inexpensive proly need to be replaced anyways and easy to install
Sounds like it will fix your problem

 

you forgot to tell him to put his car in the air and shake his front tires one by one, from side to side. If the tire has some play in it; you're right , the ball joints may be bad. Otherwise, the weights on your tires may have fallen off and it's time to get them rebalanced.