Quote: Put a 2.74 gear in it and you won't reach the MPH necessary to cause vibration . I agree with many other that it sounds like pinion angle to me, Do as suggested and check to make sure the spring perchs are good and not cracked form housing. Could still be a balance problem with the engine somehow. If the B+M flexplate is supposed to be balanced for 360 and the converter people no the converter is going in a 360. The converter may not be neutral balanced and could also be balanced for 360. I would think if both these items were balanced for 360 you would get an out of balance effect.
just had the conveter redone to zero balance
Had it redone to zero balance?????? So it was a 360 balanced converter b4?? I agree with Fred, seldom do I read old threads form the beginning but I did this one and my Brain hurts. I agree with removing the driveshaft and towing it behind another vehicle. My continued thought at this point is pinion angle or broken spring perch. Please advise all on the board how you are adjusting/reading your current pinion angle and what the current reading is.
. I agree with many other that it sounds like pinion angle to me, Do as suggested and check to make sure the spring perchs are good and not cracked form housing. Could still be a balance problem with the engine somehow. If the B+M flexplate is supposed to be balanced for 360 and the converter people no the converter is going in a 360. The converter may not be neutral balanced and could also be balanced for 360. 
I would think if both these items were balanced for 360 you would get an out of balance effect. 
