[Frank Lee]

I asked because once upon a time I considered the GV OD too. I came to the conclusion that one would have to put on one hella lot of miles for it to pay off- as you well know they aren't cheap. And I thought unless the truck is really, really heavily loaded (of course this is from a flatlander's perspective) there is no need for more gears; just a desire for a taller cruise gear. AND I thought since the goal is efficiency, adding another set of gear meshes, shafts, bearings, oil sump, weight, and whatnot to the drivetrain actually decreases the drivetrain efficiency as far as friction losses go, but ODs show an fe gain due to the tall ratios... therefore, for the lightly loaded flatlander truck the best thing to do would be gear up with tall diff gears and/or tall tires.

Actually the notion that more gears i.e. 5, 6, 7, and ? speed transmissions increase efficiency is kind of lost on me... because even with a 5 speed stick, with my mostly lightly loaded driving conditions I end up skip-shifting almost all the time anyway... well if I'm ignoring 2 gears and treating the car like a 3 speed, I think an actual 3 speed trans would be more efficient because there would be two fewer gear meshes, and gear meshes take power even when they are transmitting none.

P.S. Back in the '80s Ford offered a 4 speed m/t in their High Efficiency version of the Tempo/Topaz, NOT the 5 speed...