I have Googled geometry of driveshafts and have raised my diff (I have an IRS) to get a reasonably small angle (less than 3 degrees) on the shaft and also had to tilt it slightly to ensure the diff and gearbox end plates are in parallel planes.
Then I came across this Aus invention called the Thompson Coupling which claims to get over universal coupling problems.
They do a good video at
http://www.cvcoupling.com/
In the safety section they show what happens when one end of a driveshaft breaks free (thus the need for a tail shaft loop?)
I thought this device might be of general interest.
Has anyone experienced problems with driveshaft alignment/vibrations? If so what was the shaft length/offset etc?
Regards
martin