Ok reading pinion angle, hear is the reading from my car.

Left is the front of the car - right is the driveshaft

Angle finder mounted on the input yoke.

And the rear end

mounted on yoke

rear is left and front of car is right

Am I 3 + or 3 -.

Im using a caltrac style setup on HD springs. I already have 3* shims under the spring perches.

Car on the ground at weight except empty fuel tank. (empty tank unfortunately is pretty normal).

This may help:
http://www.4xshaft.com/tech_slopesVSangles.html

I think Im -3 according to this, as my trans is at 3 down and the rear is level.

http://www.buickperformanceclub.com/Pinion.htm

Compare the parallelism between the transmission and the pinion.

A zero degree pinion angle is when the transmission is parallel with the pinion.

A negative pinion angle is the number of degrees the pinion must rotate UPWARD to become parallel with the transmission.

A positive pinion angle is the number of degrees the pinion must rotate DOWNWARD to become parallel with the transmission.

For example, if the transmission slopes downward 3 degrees toward the rear, and the rearend is level, you have a true 3 degree negative pinion angle.

I understand you take the angle at the universal like you did and then off the drive shaft. subtract one from the other thats your angle. so you will have one neg. # and one postive #. then subtract.we run 7 degress with ss springs. not sure on caltracts. ask cal.my .02$