a "57 Apache" would be so rare as to be non-existant
the word Apache wasn't used by GM until 1958 as a "PR" name for the light trucks, 1/2T-1T, so if that's what the owner is calling it, be wary of anything else he says, especially if it has emblems that say Apache ..... "numbers matching" doesn't mean much in the 50's and doesn't really have any effect on price, but for 4000 I'd want to hear it run and see it move
look for rust in the cab corners, the door bottoms, rear bottom of the front fenders, and the low spots in the floor - anything can be fixed, but the body/paint is what'll be most expensive, and a truck with a useless engine could wind up being major work as well as expense
Bill
