Wow........ Can it go back to the 70's? That trailer is in horrible shape. The truck doesn't look too bad for its age. Truck spec sheet says its got a 391 in it at least instead of the 352(?) the listing states. The amount of corrosion in the lower compartments is pretty damn substantial though.
Those things are pretty amazing, very expensive when they came out...too expensive. P.S I don't think that is corrosion, it's a spray from back in the day.