Set includes one low pressure pump and high pressure pump. Replaces Mercruiser high pressure 861156A1 and low pressure 861155A3 The high pressure pump does not have a threaded outlet small end. This is the pump used in the ‘cool fuel’ system. The low pressure pump has a threaded outlet small end and is used in the fuel line. Fits: 1998 MERCURY MARINE Fuel Pump 4.3L 262 2000 MERCURY MARINE Fuel Pump 5.0L 305 2000 MERCURY MARINE Fuel Pump 5.7L 350 Fits with MCM/MIE 4.3L/V6 and 5.0L/V8 Gen+ and some 350 ci carburetors. two year warranty Same performance as your original pump. Set includes one low pressure pump and high pressure pump. Replaces Mercruiser high pressure 861156A1 and low pressure 861155A3 The high pressure pump does not have a threaded outlet small end. This is the pump used in the ‘cool fuel’ system. The low pressure pump has a threaded outlet small end and is used in the fuel line. Fits: 1998 MERCURY MARINE Fuel Pump 4.3L 262 2000 MERCURY MARINE Fuel Pump 5.0L 305 2000 MERCURY MARINE Fuel Pump 5.7L 350 Fits with MCM/MIE 4.3L/V6 and 5.0L/V8 Gen+ and some 350 ci carburetors.