Car has vibration over 45mph-help

[toofast82]

The car is a 91 AWD automatic. I did the carrier bushing silicone fix as well as fixed my motor mount by the timing belt. Now the car vibrates above 45mph, not excessive, but i can hear it and feel it in armrest. It also bangs in the rear sometimes when i put it in reverse.
Do you think its the u-joint? They do not appear to have been replaced any time soon, but i do not feel any excessive play in the joints?
The wheel bearings on both sides are in good shape as well.
Could the fixed carrier bearings now expose vibration in the u-joint?

 

[Defiant]

Start with a tire balance. You're right in the area where it comes into play.