My Dart Swinger Project!

I was just in the same spot with my 8.8. I tried to keep my axle tubes as square as possible during the cut, but during the process of removing material for the overall width its hard to keep them true. I basically had two pieces of 2" channel that I would clamp to either side of the axle tube...take my measurements from there. This happened more than a few times. But once I had my measurements ( 4 positions on the tube) I ground a nice chamfer on either side of my cut line. Clamped it all up and remeasured. At that point I tacked it at 3 and 9, moved me clamps and tacked 12 and 6. Every time checking my measurements. I took my material from the area between the sway bar mount and the vent.
I know youve already passed this point with the body stuff. However, Ive had good luck using nails to plug the body holes. Once they are tacked in just cut the rest off.