I think the biggest nightmare I tried to maintain was an Eaton 15-speed in a 68 Freightliner. That's the one with the 5-speed main box and 3-speed rear ends. The rears are actually electric-shift 2-speeds, but the intermediate range is achieved by putting one axle in low range, and the other one in high, and letting the power divider synchronize them. Each main box gear splits 3 times for a total of 15 forward gears. One of the company drivers missed a shift, coasted about 300 feet downhill, and then the thing slammed into gear. It sheared off a 1 3/8" diameter power divider input shaft, and I ended up doing a roadside overhaul on it 100 miles from the home shop.
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!