I agree with TINY no more than a 1/4" and try to eliminate it altogether if possible.My favorite way to see repairs done is by replacing the panel if possible but often times with these older trucks that is either cost prohibitive or you simply cant find a good replacement. My second choice is lead fill which is a fadeing art still practised only by those oldtimers that wont accept anything less(I don't reccomend because of health hazard) and my final alternative to plastic puddy is fiberglass which if done properly can out last the surrounding metal.
Hobert
