tail shaft vibration ??

I removed and reinstalled the tranny, and now I seem to be experiencing some slight vibration, and more hum than what I remember. The hum is loud enough to drown out the radio when set to a comfortable listening level at idle power, and driving down the road at 40 mph and above. The vibration increases as speed increases and I can't really tell from where it originates. Is there a method to check tranny, tail shaft and rear axle alignment. This is on a 1993 Chev 4x4 1/2 ton, the stock clutch was replaced with one that is 1/2" larger in diameter, as recommended by the clutch rebuild shop. thanks jerry