Tfltruck did a side by side gas vs diesel onntye HD and the gas did really well, so close the diesel didn't seem worth the extra.
Empty the diesel did 19.5, the gas 17.0.
Towing 7000 pounds the diesel did 10.7, the gas 9.6.
Best case in 100,000 miles that's a $700 savings on a $5000 option.
I also have heard they are in the repair bay more then the gas