Think I may have found vibration problem

after putting in the Schumacher mounts, which I was hoping would eliminate all the vibration I have been chasing for the last decade, took the car out sat. to the show and it was still there. It had changed but still there. I am sure the mounts helped the problem as the engine is in there straight now. But got to thinking that there must be something else I am missing here. New driveshaft and joints, new motor mounts, new poly mount in tranny. Then it hit me. TIRES. We had found a piece of wheel weight, the stick on kind about 2 " long on the garage floor. I pulled the rear wheels and sure enough saw where 2 weights had come off. So would that be enough to cause this vibration. So we jacked up the Dart Sport and took the tires off and put them on the Duster. It helped a lot.
The tires on there are new and balanced. So we checked the dates on my tires and they were made in 2003. Man how time flies. I am thinking that there may be something in the tire that is causing this too. Also by the drivetrain moving back about 1-1 1/2 inches in the car it probably changed the pinion angle some maybe enough to put it out of range. I noticed it got worse upon acceleration. So I am ordering a new set of B. F. Goodrich radial T/A's today and I am going to take this up to the spring shop this week and have my buddy check the pinion angle and set it like he did on the Dart. Then we will see what it is like .