Most engine/trans combinations come 3 to 5 degrees down at the rear, which should be matched by the rear axle in a LOADED situation. That means the pinion would be up the same number of degrees as the engine/trans is down. Angle gauges are readily available to address this situation.

If one has an offset pinion, both the engine/trans should be parallel to the pinion, easy to measure with proper scale.

Ed


'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires.
'47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle.
'54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed.
'55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.