That is similar practice to how Cushman used to categorise their trucksters. The first model produced in any year used the last two digits of the year, then followed it with a 10. So, the first Cushman Truckster to come off the production line in 1982 would be called an 8210; if they then introduced a different drawbar during that year the model would change to 8220, then 8230 for the next modification, etc.
You are quite possibly correct in your guess, but can anybody shed any more light on it?