My 05 reg cab F250 LB has a 38 gallon tank from the factory. Not bad with the 5.4 V8. On the other hand my 08 F350 screw SB V10 only has a 30 gallon tank which is on the small side to tow with. I have a 12 F150 FX4 on order with a ecoboost and the 36 gallon tank. 20+ MPG and 36 gallons = long range runner.