What tools do I need?

I have recently put on an adjustable rear track bar on my 4" lifted TJ, and
had to take off my upper rear adjustable control arms to get some other
stuff adjusted. When they were off a friend who was watching/helping
screwed them all the way down so now I'm having to find the sweet spot all
over again for my pinion angle.

The problem is, I just can't seem to find it anymore. I eyeballed it last
time and there was a slight shake at 65mph, but now I just can't find where
they need to be. So I'm gonna get the angle tools to do it, but I'm not
sure which kind I need. An angle finder of some sort I'm sure, but if
anyone out there can tell me what to go buy so I can measure my angles and
get everything done perfectly I would be happy! I'm tired of crawling
under, adjusting, crawling up, opening the gate to the yard, test driving,
opening the gate again, crawling under, etc etc etc.

Troy