Riders that register for the series the previous season automatically retain their race number for the following season, this included any Class Champions that decide to run the number 1 plate, that will be viewed as registering and retaining their original number for Example if the 2016 Class A Champion Andy Blomfield decides to run the number 1 plate in 2017 it will be seen as registering and retaining his #69 plate which he will then automatically retain for the 2018 season
Most numbers that are already in use / allocated can be found by looking at last years Championship tables or race results
The following numbers have been retired from the series and are not available these are #11 and #65