Vibration and Noise Issue

Just pulled everything and checked stuff out. How much play should there be in the back U joint? If I have it so that the straps on the pinion yoke are stacked on top of each other (both horizontal to the ground, so one high and one low), I can move the driveshaft up and down some amount, maybe 1/16 to an 1/8, but hard to really tell precisely. There is obviously movement though. I can physically see there there is a lot of runout on the shaft at rpm, the screwdriver thing was more to try to explain what I'm seeing. If I look perpendicular to the shaft while it is rotating it looks "warped", but progressively more at the rear than the front, so I assumed the problem was somewhere around the back yoke, but that's really all I could come up with. Anyone know what the stock pinion angle is for an E body 8.75? That's what's in the car and I set everything level when I moved the perches in, so that's where the pinion is sitting now.