So Ill be getting a full set of adj. uppers and lowers for the front and rear to run aftermarket shafts. However I fail to see how to adjust the caster on the front end without negatively affecting the pinion angle. (4in lift). From what I understand so far, Shortening the front uppers = more caster, but wont that aim the pinion down more? I need it to aim up to be in line with the driveshaft, correct?

 

You are correct. Raise the caster until you get driveline vibes, then start lowering until you find the 'sweet spot' between flighty handling and vibes. (personally, I would take the caster down another notch past that point just in case...)

Other options are the new PR housing with built in caster/pinion correction. Or you can cut and turn your current housing. Or send it to a company that will do it for you.

Spend a few minutes out on Tom Woods website for more info and pics on this.