If pulling power is your only objective Diesel isn't always the right answer. If you choose one of the small Diesels that will fit easily you may find that the power is not competitive with some of the gasoline options.
I recently read a comparison test between two brand new Chevy trucks, comparing the big gas motor against the biggest Diesel and the gas powered truck out-performed the Diesel on every measure except fuel consumption. The gas motor burned twice the fuel doing the same work. Acceleration loaded and unloaded, pulling hills loaded and unloaded, the performance measures related to pulling power, were won by the gas motor in this comparison.
Now the test was performed before the Duramax (I sometimes read old magazines) and it may come out different if using the most recent motors, but my point is simply that filling the tank with Diesel doesn't assure more pulling power.
If you want to run a Diesel by all means do so. But make sure you are realistic in your expectations of whatever motor you choose.
