You are right, Scoee. I couldn't see the belt in the original picture, but I should have paid more attention to the round cover plate on the right hand side plate. (We'll say nothing about me not noticing that the drum clutch has a steel rod linkage, where the SB45 had a Bowden cable.)
There should be a Scott Bonnar ID plate riveted on it somewhere, with a serial number. The first two digits of the serial number are the model number.
If you haven't seen this thread, you might be interested. There are also several others on the Model 33:
https://www.outdoorking-forum.com.au/forum/u...amp;Main=7650&Number=41184#Post41184
