I put a t56 in my car and it was shaking around 40mph. Got the new driveshaft balanced and it went away until i hit around 70 then a "slight" vibration is coming from the back of the car. When i mean slight its enough to notice and not bring the car over 65.
I just got my wheels aligned and balanced new ball joints and new tie rods also it has a new u joint at the rear end...
Any clue on what else it could be?