I was planning to wire wheel the frame rail and go down from back to front, then decide there. How much of the rail can I cut out before the body, y'know, drops down? lol
It shouldnt move, put the car on 4 jackstands, block and level it lengthwise and side to side, then you can measure the height of the rail to the floor before you cut measure width from other side/rail, put the new one in at the same height and width.