3 to 5 degress down .When u sent the engine put a level on the top of the intake manifold , carb removed !It should be 0 degress. The truck should be assembled as much as possable all weight on it so these numbers dont change.
I disagree with the first part of your explanation.
After rechecking the Spicer Driveline manuals I can't see how the engine being level or not makes a difference, obviously you don't want it standing up on end, but 0 degrees or 5 or even 10 is not important.
As Joe mentioned above it is important to have the engine and the pinion parallel. The engine or pinion angle in relation to horizontal has no effect on the driveline, the relationship between the components of the driveline is where it matters.
Having the truck as close to final weight as possible and assembled when you measure and correct the pinion angle is an excellent point not to be overlooked.
Grigg
