The way you describe your problem, I think you can eliminate the engine. Yes, the problem can come from your transmission, but it can be something else. Did you replace the transmission tail bushing that supports the propeller shaft yoke? It not, it might cause the vibration. The propeller shaft itself, (or U-joints), can cause this, differential can cause a vibration and the tires as well. One thing you have to make shure is the angle of your differential yoke is right, as well as the transmission angle. You can correct the angle of the diff angle by adding/removing shims between the leafs springs and the differential housing. If they are not right, (one or the other), it will vibrate. Tou can get shims in any shop the repairs leaf springs. Make shure your engine/transmission mounts are in good shape. Again, I am no expert and I' m not shure how to measure the angle of the drive train. Chryco phsyco should know better.
Robert
Thanks, Robert. Yes, the problem appears to be within the tranmission and possibly clutch disc. Engine, flywheel, pressure plate, driveshaft, rear gear, axles have been eliminated as possible cause. That's interesting that you mention the area around the slip yoke though, as this was one of the last areas I had not yet eliminated. The other day I did grab the front U-joint and moved it up and down to see if there was any play. There was, but not sure how much is allowable. I did replace the bushing in the tail shaft during the rebuild. The drive shaft angle is also interesting. The AAR's do have higher arch springs in them that would tend to change the angle between the tranmission shaft axis and driveshaft axis, but shimming it would only increase that angle.
The fact that the problem can be made to go away by depressing the clutch and releasing slowly means that something is moving or shifting somewhere. So things like unbalanced drive shaft should be able to be eliminated.
