Pinion angle and driveshaft length.

pinion angle is in direct relation to your engine intalled angle.

most mopars are set up with about 2* slope. picture the front of the engine higher than the tail of the trans by 2*.

measure this first.

you want the pinion yoke to be at the same parallel angle as the engine/trans under full acceleration load.

so if the engine is pointing up 2* at the front then you want the pinion pointing up the same amount under full acceleration load.

now your suspension dictates how much you need to compensate for axle wrap.

my caltraces called for 3-5* so i set it at 4*.

so you take your 2* upward slope at acceleration and subtract the 4* axle wrap and you get pointing down 2* under no load.

its hard for me to put it into words. but i hope you get what im saying.