Taking the following facts into account:

1 - Vibration caused by torque increasing pinion angle.
2 - Probably didn't do this when new (no one would buy them I suspect)
3 - Rear leaf springs are a bit loose and sloppy on this truck(and creaky and squeeky too!)

Could this actually be a suspension too weak to keep the axle from twisting upward? Would re-springing the leaves, new bushings, etc, fix this if the truck could stand having a little suspension work done on it anyways??? At that time I could add shims too.

Just some thoughts I would like a sanity check on. Especially #2. I just assume they didn't do this new....

PS: This web page has some great stuff about this on it.

PSS: Excuse my ignorance on double carden shafts Jerry. The above page straightened me out on that too.(-;

NCDiesel