Slide 3 December 30, 2015 By admin F450 550 650 platform V10 6.8L Gasoline Fleet Before Conversion Specs Monthly Fuel Cost $ 2, 666 Safety Average Emission High Engine Wear and Tear Average Warranty Coverage Full Compressed Natural Gas After CNG Conversion Specs Monthly Fuel Cost $ 800 Safety High Emission Low Engine Wear and Tear Low Warranty Coverage Full