You'd know if the pinion angle was off, you'd have a vibration at or above certain speeds.
What I was taught reagrding angle: With suspension loaded, ie as it would sit to be driven, the trans output and pinion should be equal but opposite. If you trans output is angled down 3 degrees, the pinion should be pointed up 3 degrees. Max should be 5 degrees. Keep this in mind as you do your assembly.
Devin
