In a message dated 96-09-13 23:41:34 EDT, you write:

<< It occcurs at random right around 45 MPH. >>
Usually, an imbalance criveshaft shows up at slow speeds, but a defective u
joint will cause vibes at the speeds you mentioned......only problem is, no
ujoints. I would better guess that the wheel weights may have blown off.I
have had this happen many times on my BMW chrome rims. Check for a shiny area
where the weight may have been, and make the shop warranty it, if the tires
are new.Hope this gets it. 

PS: Make sure the shafts are bolted tight at all surfaces.

Ed Berroth
84 Westy Wolf
87 Stinkcrow