I'm sure someone will come on with a better explanation, but "Free Wheeling" is Overdrive. I had it on a '57 V8 3100 forty some years ago.
Seems that I'd pull out the chrome OVERDRIVE t bar, then I either mashed the gas pedal or released to make the solenoid engage or disengage the O.D.... The O.D equipped trucks had 4.11 rears vs. the standard 3.9's .
I'll bet if you get yourself a 1963 Truck Operators Manual reprint it'll tell you how to operate the system...
