The M Pump Fuel Supply/Lift Pumps have Disc Valves in side instead of the Solid Plastic sort of T shaped cylindirical Valves with separate Springs that are on the MW Fuel Supply/Lift Pumpumps and the Hand Primer is on a different spot on the Body of the Pump.
I thin the M Pumps Fuel Supply/Lfit Pumps also use only 2 studs or bolts to hold them to the Fuel Injection Pump; the MW uses 3 studs or bolts.

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84 300D, 82 Volvo 244Gl Diesel