[jltait]

IF it is a long bed I would say zero, (I do have experience with the long beds)but this may also depend on the driveline angle. Just turning up the pinion is not a really good way of dealing with driveline angle issues anyway. the angle at the front joint and rear joint should be equal. Meaning if you turn up the pinion x deg's you need to drop the tailshaft of the t-case the same. Now this is all general information. In the end how much correction if any depends on the powertrain length, driveshaft length, and the current operating angles of the u-joints. In some cases with short wheelbases (k5) and this amount of lift the only way to get rid of vibration is to add a CV to the front of the shaft then point the pinion up at the tailhousing of the t-case with a .5-1 deg operating angle. The eliminates the need to have equal angle at both ends.
JLT