from the angle that stuff was sprayed, seems the focus was the floor pans. As such, wondering if that was the dealer applied Rusty Jones treatment from the time....sprayed via a wand from below with car on a lift or tech in a pit below car.
paint marks on drive shaft still show colors. part # tag still on LF coil spring. pitman arm shows where label once was at centerlink end. wonder if rear still shows red letter "P" or traces of outline, if it is a posi rear. to me, that's some of what I'd expect to see on a 24K mi example. we don't see the rest of the car though.
to me, looks like light surface rust on balancer ( what wasn't sprayed), front brake caliper, dust shield, etc. in pic #2, see how floor pan and top part of frame was blasted with heavy application of undercoating while lower part of frame rail was not done. similar undercoating technique in pic showing y-pipe clamps at pipes to crossover muffler. notice how undercoating not applied to outer areas around clamps. only driveshaft tunnel area and wide open forward section of floor pans. angle of spray hitting brake prop valve and plate show sprayed from rear and below car.
the car very well may check out to be a 24K mi example. it will be time consuming to heat and remove the undercoating treatment. Frame, rear axle housing, suspension links, sway bars, etc had such a light spray of black paint that didn't last long. dry ice cleaning of the underside is a great thing but it doesn't do undercoating. thinking mild heat from a heat gun - just enough to soften the coating to permit it to be peeled off. not to overheat it to where it smokes and smears with a scraper.
at 24K miles, seller should have a paper trail to go with the car. original window sticker and dealer invoice would tell more. I'll conclude the sloppy undercoating was just Rusty Jones done at time of sale by dealer rather than current seller unleashing a spray bomb under car to hide something. spray bomb would have gone everywhere. angle of application, areas sprayed, over-sprayed and areas areas not covered to me support wand spraying from a distance. tried to find a 1980s pic of Rusty Jones application, quick search found this pic below...