Hi Steve, thanks for posting some good pics, mate. After speaking to the gentleman re: when the Model 45 was first manufactured, he told me 1966, and the serial numbers on the
first machines started from 00000 and ran sequencially. Thus with your machine, we can definately say yours was the 867th Model 45 produced!
It is a pity we don't know how many machines were made in a year, eh!
UPDATE: We now know this information was incorrect. No exact date is possible for any Scott Bonnar.