I think they're all LH thread on RH rotating engine.
#5
ducatiman900ss
model # 917.387151
i erred on part #....650816 is correct
#6
StarTech
143.975500 TVS115-62106B engine
RH threaded
Side note boy has Searspartdirect started screwing up even worst. Their IPL said has a Briggs engine when the owners manual says it came with the above Tecumseh engine.
PN given by OP is a Tecumseh part.