The appearance of the 6 and 9.5 is very different, bugn. The 9.5 were the "low profile" engines and don't look even a little bit like any other outboard except the Johnson MQ series 9.5s.
I think you probably have a 10 HP from the late 50s or early 60s. I don't remember what E'rude called them, but they were fine engines. They did look a lot like the 18s.