Though it is unlikely that I would or even want to, it would still be nice to have the option to take it on the highway. Currently, the few short distances I took on the highway, it felt most comfortable at 70-80 kmh. If I were to take it on longer distances, a minimum of 90 would be better. It is a 1953 GMC 9700 3-ton grain truck with a regular 4-speed manual and 2-speed differential. The engine has been changed to a '66 292. Apart from not having the engine at high RPM, I heard the 292 is already bad enough on fuel. Apart from completely changing the driveline, are any of these an option: - Are there any add-on overdrive units available for 3 tons? - Can a 2-speed diff have the gears changed? - What higher gear transmissions would work in it? - Or what rear axles would bolt in? For the most part, I'm just curious.
