We have a 145 school buses with Cummins, Cat, IHC, and the Mercedes engines all of them hooked to the Allison automatic. The older Cummins with out electronics is a good reliable engine, under powered 190hp for a loaded 65 passenger school bus. You are lucky to run 60mph. The 3116 Cats are the same way only slower. Our 466 IHC are trouble free and pull pretty good even though they are 190hp. Now the '08 Cummins will get out and run, its slow getting there, but will hold its own on the road at any speed. Mercedes are very reliable and fuel effecent, the 3126 is Ok but I wouldn't want one.
I would stick with IHC due to the chassis and brakes. You just can't hurt them, and believe me, a school bus driver will hurt anything! The Freightliners would be a good choice with a Cat or Mercedes engine, although they are harder to work on. Anybody with a slight mechanical knowledge can work on a 466. Joe
