MerCruiser 90747A3 87-91019A3 Distributor V8 5.0L 5.7L 305 350 260hp 898 198hp 3hp The Part Number of lower

The Part Number of lower mixture knob is 377219

Medium-Rough

47957 Vent Hose Connector (NOT INCLUDED)

so it might have been an automotive application

Quick rundown of the parts here:

MerCruiser 90747A3 87-91019A3 Distributor V8 5.0L 5.7L 305 350 260hp 898 198hp 3hp The Part Number of lowerPart Number(s) Included MerCruiser Distributor Assembly 97401A3 Superseded Related P N: 90747A21 90747A25 90747A27 90747A43 805185A43 805185A36 Sierra 18 5470 Newer Models Had a Distributor Mounted Ignition amplifier and this base does not have those mounts so pretty much this is only applicable to 1986 1987 & older models. Sensor 87 91019A3 Is still installed in this Superseded Equivalent Related P N: General Application Compatibility Generally found