This is the one you want: Macklanburg-Duncan 92346 SmartTool Module Only. There are a number of places to get one, but I got mine at Amazon:
http://www.amazon.com/exec/obidos/tg...043241-4882567
The precision is incredible in tenths of a degree. I used my mine for the set-up on my 1/3 scale extra. At about $90.00, not cheap. But a quality tool. Does make the various incidence setting tools seem overpriced. Also actually works great for work around the house, but that's up to you.