On the 29 tudor bodies there is a wooden block that goes between the frame and each of the body mounting points. Weld the 3/8 plates on the underside of the top of the frame then box it. Set the body on the frame. Get everything lined up then center punch the holes in the plates through the body holes, drill and tap for the 3/8 bolts. This keeps you from having to hog out the holes in the body to line up with the tapped holes in the frame if something is a little out of alignment