I have a similar vibration with my 68 LeBaron. The vibration frequency
seems to be proportional to vehicle speed, so its definitely related to the
brakes. Phil is suggesting the possibility of wetted drum shoes from past
differential leakage. Guess its possible, but my 68 sedan that still has a
small leakage on the rear left drum does not have any vibration, but it
does have a very slight pull, as expected. My guess is that my problem is
related to a warped rotor. It seems to happen after the brakes have been
warmed up somewhat. Any suggestions, especially from Budd braked Imp drivers?
D^2