FOR 2013-2018 RAM 3500 WITH-- 6.7L DIESEL. FOR 2013-2018 RAM 2500 WITH-- 6.7L DIESEL. FOR 2013-2018 RAM 4500 WITH-- 6.7L DIESEL. FOR 2015-2018 RAM 5500 WITH-- 6.7L DIESEL. The Diesel Fuel Water Separator / Fuel Filter location is in the rear of the truck next to the fuel tank.