Even the ones with the SAE-style round front housing can be adapted to a stovebolt engine with a special bellhousing, but those adapters are scarce as a chicken with lips. Clark, Spicer, and New Process all made 5 speeds in direct and OD top gear configurations, but they weren't used in rigs much below 2-ton size.
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!