I’m going to go a little later model Merc 200, full gear shift. I was thinking auto-tranny too; but the thing that doesn’t figure is the spark plug wire shield. Also, auto trannys had a solid, full mag plate. I was surprised to see that drag link system on later engines!
As for the first two, I think that’s going to be from a late 80’s OMC three cylinder, probably the same one as where the VRO pump came from? Fleetwin will know for sure.