Diesel Tow vehicle options

[Chevy454]

Dad used my 2500HD with the 8.1/Ally/3.73 combo to pull our 24' enclosed with a boat load of tools & the too dog-gone heavy Red Alert inside...it's all hills & curves between here & Collinsville, and he said he got right around 8mpg...just a tad below the 10mpg we get with the Dmax...would be interesting to see what these trucks would do if they ran around flatland for a few days? But, he said he might actually prefer the 496 over the Dmax (at least with the little trailer)...except for the tiny fuel tank since it's a swb...guess that 90 gallon aux tank on the Dmax has spoiled him!