Hotchkis 1811 1994-1996 Impala SS X-Tend Rear Suspension - Manual (Page 13)

The simplest rule of thumb is:
The centerline of the differential pinion should be parallel to the centerline of the engine’s
crankshaft without being the same line.
So, the first thing to do is to find out the angle the engine’s crankshaft is sitting at. One way to
do this is to set a digital angle finder on the front crank pulley or harmonic balancer. Record this
angle. Next, set the digital angle finder on the front flat face of the differential yoke. This angle
needs to be the same as the recorded crank angle. Adjust your Hotchkis trailing arms to obtain
the angle needed.
Tighten all hardware and drive the car. Test for driveline vibration by accelerating.
If there is vibration during acceleration, then the pinion angle is set too high!