Gear ratii? I thank God for not making me a word nerd. That don't hardly look right, ratii. Darn those old penguins for teaching me Latin. Heh. Okay, here it is: My truck, with its 5.14 diff ratio, is too slow. I want to cruise gently and economically at 50 - 55 mph. My (SM420) transmission's gear ratios are too widely spaced; I am uncomfortable with - when fully loaded starting up a long grade - using my engine's entire powerband and both verges to get up to the next gear. I live in mountainous terrain, that ain't gonna change. I intend, now, to keep the original engine - or one like it - in my truck. That ain't gonna change either. So here's the plan in its current incarnation, subject to change without notice: a 4.10 diff from a '71 3/4-tonner, and a NV 5-speed (overdrive) tranny from a Dodge Cummins. The NV is a much-maligned, but perfectly strong transmission abused by uninformed drivers who believe that the monstrous amounts of torque generated by their overpowered engines makes it okay to stay in overdrive when they should downshift to direct drive to preserve their powertrain.
This combination, with my 235/85R16 tires, will allow me to cruise at 55 mph with an engine speed of barely 2000 rpm. If I downshift to 4th the engine speed will increase to around 2800. This, I think, will give me exactly what I can live with forever in a working truck which may one day be called upon to go transcontinental.
At least, that's my theory, in its current incarnation, subject to, etc.
I want a truck which looks as close to original as possible, but works better. Opinions, anyone?
