Added two more clamps, (can never have to many clamps), the blue ones to the rear setup to hold the frame down to the axel in the vee block.
Tack weld side to side then check with plumb bob to keep pulling it back and forth till it quits moving and ends up on the line.
I had to reheat one tack to get it to position properly. Onec it stoped moving and I had welded as much as I could in this position it all get taken apart to finish the welds.