moving the rear end

When I back halved, went 4 link and coil overs, tacked in; left it for 20 years. Came back to it, and to refresh my memory, as all the marks I had put on the floor were gone, did some quick measurements, and crapped.
1/2" wrong. After about 16 hours of plumb bobs and double checking, and talking to BBD forum... the body is off. As usual, I found out.
The only thing that matters is wheel base.