Where is rusted out at? Hmm. The low spot of the rear floor where the floor goes up to make the upright that goes under the rear seat, both sides, normal next-to-last-crossmember rusted out, replaced with sch. 40 pipe, passenger side rocker, GONE all the way fromthe front fender to the rear quarter, both rear seat belt attachemnt points located by your hip, the bracket that keeps the rear seat from flopping around, rotted loose, area right behind the drivers side strut tower "pocket" under the hood, rusted out all the way back to the firewall, and down to the frame, piece located behind the grill, that runs vertically and ties to the lower valance, rotted at both ends, body tub under the tailgate where the wiring goes through, just about gone. Probably some more that I haven't seen yet, I'll wager. Poor little rust bucket.
The crazy thing is, almost all of the nuts and bolts still undo with out too much arguing ( soak them in some PB Blaster for a couple of days, and get happy with the 3/8" drive stuff. ).