DWeikert wrote:
No, it was just the way the truck was geared and how it responded to loads. In hindsight I realize I probably could have minimized the gear searching buy downshifting out of overdrive when I approached any grades. But I have yet to need to do that when I made the trip in a diesel. Anybody that hasn't worried about engine temp when climbing mountain passes at speed in summertime hasn't done so in a pickup or RV with with a gas engine. Likewise anybody that thinks a gas engine has a decent engine break has never driven a diesel.
Keep in mind the OP asked about a gas engine for TC hauling which isn't even in the same league as heavy trailer towing. I have none of the concerns you describe with a 4k lb camper, 2k lb trailer and a gas engine. The cooling system is designed to handle it and it doesn't get warm. The grade braking does just fine on downhills with that light load.
Much of this may be due to the engine (8.1) and transmission (Allison) which seem to perform exactly as I'd like them to. It also has more HP and most of the torque of the diesel option in its time. That experience may not be the same with other setups.
Mileage? That's a given win for the diesel. I get about 8 to 8.5 the couple times I've bothered to check with a mix of 65-70 on the freeway and 55-60 on secondary roads.