the studgun would be my first choice; I've burnt up 5 of em in my 17 yrs in the business! with the stoutness of that metal, start small, just use light pulls...better to not pull enough and have to make another than to pull too hard and stretch it! Once again, the metal in those trucks is pretty tough, so with the studder you should be able to work most of it out and keep any bondo work strictly as a smoothing coat-the way it should be!
