Thanks Bob; I appreciate the assistance.
After a couple of pleasant hours looking this over, I found a couple of things:
The motor was seized up tight; I gave it a "bath" in some WD40, worked it a bit, then cleaned everything and the motor now runs beautifully on about 4-5V.
If this the "slotted nut-head" mentioned earlier, it certainly will need to be attached, as it's now just kinda "floating" around and will fall out if you're not careful...
I waited a long time to score one of these, and I'm in no big hurry to get it "road-worthy" (yeah, right!). As it is now, I think it makes a nice display piece. Looks much better without the huge motor in the cab:
I'm guessing this was not considered a "high end" model at the time, yet it really has nice details...
All in all, a nice old model I think, for less than a hundred bucks...
Mark in Oregon