They sale camber gauges on ebay.

http://cgi.ebay.com/ebaymotors/BALL-JOINT-TIE-ROD-STRUT-ALIGNMENT-CAMBER-gauge-NEW-_W0QQcmdZViewItemQQhashZitem1e6203b33fQQitemZ130493428543QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

I use the string to align my cars. I have no tire wear and the car drives straight. All my other vehicle have been fine with aligning them this way, but the E420 has me puzzle with the tire wear. I am 1 degree negative on the rear and the stock bushing look great. I guess once it has tension put on the bushing it must give a little.

I could not get the new camber arm install because I don't have a new tension pin/sleeve to put on the new camber arm, so I put the old camber arm back on. My next step is to purchase the SPC camber kit.