Not complete but should give some clues, note how the rim has pairs of alternating dimples on 2 rows on your rim.

https://draganfly.co.uk/wp-content/uploads/data/pdf/Rims%20and%20spokes%20BSA.pdf

Draganfly refer to the late A10 early A65 wm2 18" rim for full width hub as 7 (oddly its later seen as 7A part no 41-6006), so you should try and see if it matches and then see all the models the 7A fits which includes ;ate B31/B33. There is another error where a 7A is listed as a 7B but 7B is for a 19" rim but same hub.