LarrySS,
I am living with the same thing. Not a problem, just use an extension and a socket on the opposite side and it is a one-man-job. My car is lowered slightly, so that makes it a little bit of a tight reach to get the socket on initally, but doable. Once you get the nut fairly tight, you can tighten it to spec without having to hold the bolt. Your alignment guy will probably cuss the first time he encounters this. I strongly urge that you watch him do it right!
The bolt is a 1/2-13 x 2.5" flange head. Grade 8. There are splines right below the head on the shaft. Use only the correct GM part, 10262655. BTW, one of the replacemets I bought had the splines too far away front the bolt head to contact the sides of the hole in the bracket! That's quality.
Also, not all of the bolts that I replaced "bit" into the holes even though I pressed the old ones out.
Tim