I'll start with what I've done since the previous owner only replaced the alternator, radiator, hoses, belts, battery and one coil pack.
I changed the transmission solenoids, alternator, fan clutch, radiator, hoses, thermostat, LBJs, rear shocks & springs, steering rack bushings, sway bar bushings and inner & outer tie rods. Those are the main things. Tons of little thingies and of course regular maintenance stuff like brakes, fluids, filters, plugs, wires...etc. also plenty of interior upgrades from the junk yards.
Most things are original to the truck including the engine and transmission.