I have a 1966 T-Bird. Recently, both the engine and tranny have been rebuilt. Now there seems to be a vibration in the front end when I reach about 45 - 55 mph. It feels like it is in the front end (I can feel it in the steering wheel). The driveline seems to be tight and I have had the tires balanced. Any other suggestions??? Thanks in advance.

Driveshaft balance can affect it also. When older the weights can crack loose and fly off. Checking the balance wouldn't hurt. If it's in the front - do you have front drum brakes?