Looking at a 1987 fj60 with 139k that runs very well and is bone dry on the bottom. I checked the frame for rust when I looked before, and I'm going back tommorrow to look again. I kicked it on the sides beneath the doors, solid, but flaking (1 cm diameter). What should I be looking for when I go back with a screwdriver and a hammer? I know nothing should sink in, but I'm not sure I'll be able to tell the difference in pitch between a good ping and a bad ping. The two longitudinal (don't know the real name) bars on the rear of the frame have been coated with rustoleum a few years ago, they aren't as rusty red as towards the front. I've read conflicting things about painting the underside with paint. Is it worse because it's just trapping the cancer, or can it a reasonable solution to increase the life of a New England frame. I'm planning on driving this rust bucket because it's in my price range and I won't have to worry about cancer on a rust free cruiser. The frame is what I'm most worried about, so what is the best way to thoroughly check for frame rust?