[Kevin in NJ]

Shrinking with a torch should only be a last resort by someone with experience. You should not do that on a high crown area like the upper area on the door for 30-31.

Let restate the above, do NOT use a torch unless you know what you are doing. Even a small shrink does more distortion then you might expect.

A shrinking disk is the tool to use. It is slow and effective. Research it.

If you want to be able to do patches where the weld joint is not easy to see in bare metal you start with learning about stretching and shrinking metal. Once you understand how that works you will find you look at repairs in a different light. You also learn heat shrinks are very dangerous and must be carefully planned. Then only do one at a time and let the metal come back to the same temp before deciding on the next shrink.

That's my advice, take it as you will. I have learned the hard way.