http://www.rosslertrans.com/Tips/Pinon.htm

 

I put 4* shims in mine and got a pinion angle of -0.5 so I left it at that for street use.
At first I put in 6* shims to correct a pinion angle that was 6* high. But that brought the driveshaft angle down as well and I ended up with a -3 to -4 pinion angle which I thought would be to much for street use. I switched to the 4* shims and it worked out to what I wanted for street driving.

 

I just bought it. It looks a bit cheesy. The dial doesn't move with the bubble.
You have to center the dial in the middle of the bubble. The bubble isn't small either which is why it may not be exactly accurate at all times or in tight areas.
I guess you really can't complain since it's only 5 bucks.
The competition engineering one may be worth the money if you used it somewhat often.
Though you can't beat the Craftsman's magnetic abilities that it has over the more expensive ones that do not have it.

Jim