I bought the Longacre alignment tool because I cannot trust the local shops to understand 40yr old technology..or lack thereof. I spent night and day for 2 weeks asking questions. I was between the Fasttrax and the Longacre. Reason I didn't go with the Fast Trax is because its a bubble gauge. I need actual degrees. A bubble will give you an approximation of +/- 2ยบ. The Longacre gives a dead on degree point. Its a simple calibration that you do every so often with a flat level surface and as already mentioned, it has carpentry uses.
The negative side of the Longacre is the mounting feet. My Charger has 17x8 Magnum 500s. I do not have a curled wheel lip where the feet can "grab" on to. I instead had to secure it firmly in place with a cargo strap wrapped around the tire from rear to front. But doing it this way gave me peace of mind anyways that it wasn't going to get jostled loose and that sensitive calibration level wasn't going to strike my concrete hard. When you are in there working behind the tire and adjusting the UCA bols and your knee whacks the alignment tool assembly, you have to start all over again.
All in all, I am happy I made the purchase. I have done two cars with it so far and it pretty much sits in its case waiting for the next job. Does Caster and Camber...Toe I did it another way....4 jack stands and a long piece of twine. Tie one end of the twine to the jack stand at the Front Driver and run the twine to the jack stand at the rear driver tire...Set the twine here with one loop around the jack stand lift and that it makes contact with the tire so the twine touches both fore and aft of the rear drivers tire. Send the twine to the Passenger side tire, tie it off as above and make contact with the fore and aft of the Passenger side tire. send it forward to the Passenger side front tire. This is where the eyesight and a measuring tape take over. The twine needs to make contact with the aft portion of BOTH front tires, so adjust the jack stands accordingly. Adjust the tie rod end so you achieve 1/16" toe IN on both sides. 1/8" total toe IN.
Hope that helps
