The rear axle has to be fully loaded, so you'll have to put jackstands under it. The way I've seen it done by Steve Spohn is to measure the angle on the DS, then measure the angle on the pinion, by putting the level under the torque arm mount (flat bottom). The resulting angle (driveshaft minus pinon) is what you are setting. Should be a "\ /" pointing down. The difference of -1deg should be good. I never measured the stock setup, but I suspect it was between -1deg and "0".
It's very hard to read the little $6 angle finders with any accuracy, but I've set mine that way. Steve had an electronic angle finder that he just placed in both locations, pushed a button and the reading for the difference between the two angles showed up on the display.... for my current setup it showed -1.8 degrees. That's a setup capable of 800 ft-lb (5,000rpm with a 300-shot) on launch, with the rod end on the TA.
