My recollection is that when the kit was initially released, back in the sixties, it was possible to buy a separate kit to motorize it. (No RC gear, presumably - but one or two motors, a battery box, shafts, screws, etc.) My memory may be completely messed up there, though. As I remember the kit initially cost $5.00, with several dollars more for the motorization kit - far more than I, at the age of 12 or 13, could dream of spending on such a thing.
I haven't seen the kit outside the box for many years. My understanding is that it's pretty crude by modern standards - but quite a nostalgia trip.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.