I drove one for a lot of years in a B-73 Mack with a 262 Cummins Diesel- - - -once you get the hang of shifting it, it's hard to imagine not having one. It's particularly useful when you need a couple of intermediate speeds when pulling a heavy load up a hill, as every main box gear becomes three speeds. Once we got the truck moving, all the shifts in both boxes were done without disengaging the clutch.
Jerry
