When you go look at it, take one of those small magnets like the ones on the ends of small screw drivers or pens. Magnets wont stick to rust. Great way to see through the paint. Fiberglass can hide rusted out areas but will fail the magnet test. Very common on some quick turns. Floors should have the "ribs" in them. If the floors are just straight, flat metal, they have been replaced....poorly. Get a good light and look at the inner rockers. Often the rockers can be mudded to hide rot but the inners are often overlooked and can tell you a lot. The single biggest problem...I mean the BIGGEST problem on these Broncos is RUST. Engines, wiring, all interior, glass, drivetrains, suspension are all easy buy and replace jobs. But RUST in the body gets very ugly very fast. Unless you have a lot of time, are a good welder, and have the space and tools to gut the body, rust will put you wayyyy upside down very fast if you require someone else to do it. If you find that there is not a lot of rust (rust can easily be hidden....see above), then it is probably a good deal. If there is excessive rust, I would pass .