Vehicle for pulling a 12,000lb 5th wheel loaded.

it depends a great deal on the type terrain you travel, hills and mountain's then yes a diesel for sure, flat terrain with only sight pulls then the gas job is fine. Don't let the word dually fool you, the 3500's also come in single wheels to each side We have a fiver that weights the same as yours I tow it with a 2500 HD gas job This pic was from a trip to Savannah Ga Not trying to stir the mud but don't forget your cargo weight including the pin weight of your fiver