Bob,
I had some problems with this too. There are a couple of things that I can recommend as follows:
- Use a ratcheting type of luggage strap to pull the body inward. You can hook to the body on the other side or even to some place on the frame. It does not need a lot of force either.
- One easy way to lift the body edge up is to attach a strip of plywood or 1 x 4 length-wise along the bottom of the body on the side that needs to be lifted perhaps 6" or so above the floor. You can use sheet metal screws to hold it to the body ribs. I am assuming the inner skin is off by the way. You can then use a piece of 2x4 and a block of wood as a lever to lift up on the strip of wood. The point is that you want to avoid lifting the body edge from the bottom of the c-channel becaus it is kind of easy to bend so that it is harder to get the floor back in place.
I used a framework of 2x4 crosswise to both hold the body together side to side as well as to keep the body up. I am attaching a photo that shows the gereral idea. The cross pieces are at a good height to allow a small hyrdralic jack to be set under any part I want to lift up. The short vertical pieces are 2x4 attached with 1/4" plywood so that they are removable if they are in the way when I am working in a particular area.
Let me know if the above is not clear enough and I can explain further.
Malcolm