Description Genuine Fleetguard FS1251 spin-on diesel fuel/water separator filter for Cummins 4B and 6CTA diesel engines and various Case IH and AGCO applications; 20 micron filtration with 96% efficiency by SAE J1985, 90% free and emulsified water separation, M16 x 1.5-6H internal thread, 76.71 mm outside diameter and 142.9 mm overall height; cross-references Cummins 3286503 and 3843760 and equivalents including Baldwin BF1226 and Donaldson P550248.