The only compact-size 2-speeds I'm aware of were the Columbia models that were made for Ford passenger cars back in the 40's. The frame shape left no room for an overdrive trans, so they made a planetary-gear rear end to take the place of the overdrive. For OD ratios in a 3/4 or 1-ton, try to find a Clark 5-speed with OD on 5th gear. Passenger-car transmissions like the T-5 will be too lightweight to handle any truck duties except cruising around with no load in the bed.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!