G'day David_M,
In all truth, I was a bit amazed that this part was still available here, for such an old saw!
My family had an Outdoor Power Equipment business in Northern Vic, that had a Mobilco dealership in the 1970s [until they closed down in 1976], and even then, the Canadien parts we could get were aftermarket gear like Tillotson carby parts, and bar/chain/sprocket stuff.