Go back to the dealer and tell them you want your truck fixed tomorrow, or you want a new truck, Insist on it. If that doesn't work, go fucking ape shit.
Anytime you add weight or tow load, it's going to be harder on powertrain components, but being in 6th. gear, that's just the transmission keeping the engine in the power band so you're not lugging the hell out of it.
Nice truck. I'd drive that all day long. ?
How does it run? If you're really concerned about milage, I would start by weighing everything, because that's what's causing your poor economy, dragging all that weight around. At sea level, that truck should run very well. I would find a scale, (truck...
So regardless of shit ground clearance and wheel travel, the wider the axles and tires, the more bad ass it must be. what a piece of shit, lol. In a perfect world where appearance is the only thing that matters, the only auto manufacturer in the world would be Hot Wheels.
Why do you want it to shift out of 6th. gear and not down shift on hills? That's what a transmission is supposed to do. You put heavy MT 35" tires on and it's just compensating. Turn up the music, have a few drinks and have some fun.