39 Tudor Vibration

Has anyone got any ideas ?
My mate has a 39 tudor which we have just transplanted a 8ba & c4 into with open drive diff conversion on the original diff, now when he drives it it vibrate really bad over 40mph.

Specs Motor & Trans can out of a 49 woody as is & running perfectly.
49 8ba edelbrock heads & triple carbs,Mallory points dizzy &
MSD, the engine was balanced & with new everything (no expence
spared) it has a Flat-o-matic adaptor kit & early C4 trans, we
bought & fitted an open drive conversion for the original 39 diff,
we had to modify the sump to fit & got a wish bone splitting
& trans mounting kit from speedway motors.
We have had the drive shaft shortened & balanced. We have tried shifting the trans into nautral when driving & the vibration goes away!
We have had the drive shaft re-balanced & now we have pulled the motor & trans & removed the gearbox & found nothing the torque converter can only be bolted up in 1 location !

Any Ideas would be very much appreciated

Cheers

 

bump

 

If you are sure the engine and trans were good in wagon,what was the rearend,open like 8 or 9 " or stock with kit to open.
I would go with like 8" with parllell springs.

 

Because you say the drive line vibration went away when you shift into neutral indicates that this is in the driveline not the engine. You failed to indicate how you located the rear axle after you removed the torque tube, did you use ladder bars or do you have a parallel leaf spring set up? My assumption is that you have a u-joint alignment problem that gets worse as the speed increases. This would indicate the u joint angle between the transmission and the rear axle is incorrect and creating a vibration when the u-joints bind and do not pivot correctly. Before any more guessing goes on tell us how you located the rear axle after removing the torque tube and give us an idea of the angles that the drive shaft and the pinion conversion make in relationship to a horizontal running front to back thru the center of the rear axle.