Aligning the Body to the Frame is a very important step. This must be done before mounting the engine and transmission.
On the front end of the car and using a level, place a piece of tape on the finder that is level with the top of the two foreward frame rails.
Place a mark on the tape that is level with the frame rails. Do the same on both sides.
Then measure the distance from the frame rails and the outer side of the finders. Ours was 16 3/16 after both sides were even.
On the rear of the car do the same.
Ours measured 17 1/4 after they were even.
That takes care of side to side. Front to back is done by centering the wheels in the wheel well.
By moving the transmission and engine forward or backward we aligned the exhaust pipes through the body.
Note the tape around the pipe for protection.