Ram 2500/Ford F250/Chevy 2500-GAS Engines Towing

Not the size motor your asking about but just giving some specs out there.
We were towing with a 2012 Dodge 2500 mega cab 4x4 with the 5.7L

We pulled our 40' Cross Roads bunk house 12,000#

I added the bully dog has tuner to the truck and our last trip we took with the truck was 8hr drive and we were getting between 10-11mpg. We had also added a air raid cold air intake and a flowmaster muffler.

Had plenty of power to spare.

Probably doesn't help but I sure like the 6.4 in my Challenger SRT!!