Considering that they are ROAD tractors, not a tactical truck, road speed IS important.
Besides, they only revamped to the auto transmissions at a later date, so road speeds where all around.
I just do not like running a truck at the rated rpm just to try and keep up with traffic. Kills the fuel mileage, runs the engine raged, and it just uncalled for.
That NTC 400 should be able to purr along at 1600 to 1800 rpm.
Heck, the newer ones like running at 1250 rpm!
Starting to think that regearing the axles is the best choice for a 920... Hate to loose the low gearing though. Would much rather have the double overdrive.
If that allison 7 speed is a double overdrive though, that would make it a NICE setup!