The gas tank on my 1952 Chevy 3100 Pickup had a hole in it. I tried to patch it up with Caswell sealer from the outside, but that only lasted a few months because I just dabbed a bit on the outside of the tank. After a bit of research, I realized that the gas tank was from a 1965 Ford Mustang, and so I picked up a new one at Carlisle at the Spring Swap Meet along with a new sending unit. I cut the float and sending unit off, but kept the pickup tube and sock filter. I cut a 1 5/8 hole in the top of the tank to mount my sending unit, and now it looks and works great. I then took the cheap plywood bed floor off and mounted the empty bed back on the frame using the right sized bolts. If you take a close look at the above pic, you will see the bed mount on the right rear is significantly lower than the left side mount, so the bed had a lean to it. I shimmed it up for now, but I might cut it off and re-weld it higher next time.
The next project is to make a nice new wood bed that might lift like this one...