Diesel vs gas......................

With the exception of the 3500 DRW (and then only with the allison), the 8.1 is rated the same as the DMax. Part of the reason, I believe, that the DMax is rated higher in that one case is because it develops more HP than the 8.1 at low rpm.

This part of your argument is flawed.

It does not matter which truck/cab configuration you get the Duramax in, all current DMax's are the LLY with 310HP and 605TQ. In addition, all current trucks with the Duramax have the same 3.73 rear gears and all of them with automatic transmissions have an Allison. Therefore, the Duramax will develop that same higher HP at the lower RPMs than the vortec 8100 in all 2500HD and 3500 configurations. The 2500HD and 3500srw trucks both have the same 22K GCVWR that has been available since 2001 with Duramax/Allison and 8.lL/Allison trucks (only when the big block is paired with the 4.10 rear gears). Since it would be nearly impossible to max out the GCVWR on 2500HD and 3500srw trucks without exceeding payload capacity through 5er or gooseneck pin weight, it does not make sense to up the GCVWR's of those trucks with the newest version of the Duramax. With the 3500drw however, it is more likely that one could get to the GCVWR, while still remaining under payload capacity. Therefore, those trucks are rated for 23,500 pounds of GCVWR with the diesel. So, you have a diesel engine with a 3.73 rear end that is rated for 1,500 pounds more towing capacity than a big block with a 4.10 rear end.

I agree that torque is a different type of measurement than HP, but when you are considering the application of torque and HP in the case of light duty trucks when towing, the low end torque advantages of the diesel overcome the high end HP advantages of the big block.

I was merely pointing out that with

ALL OTHER THINGS BEING EQUAL

the higher torque diesels have an advantage when towing, even though they have less horsepower.