Spider.. welcome to karting.. I am the Vice President of the Norht Florida Kart Club at the 103rd street track in Jacksonville
www.northflkarting.com . There is no real process in choosing a number for your drivers kart. Pick the number come to the track and see how it goes.. Usually if there are two the same numbers.. one will put an x next to there number. The track uses electronic scoring and the number is only used to register... you got a transponder to race and that will be the tell all for your race results.
You can run a three digit number if you like.. but the room on the side of the kart is at a premium. It also needs to be clear a visable to track workers and the tower scoring.
Please if you have any other questions about what you need to do or bring with you.. get in touch with me on here. or send me a text. 386 503 9068 Mike My son also has a Margay Kart dealership. Parts, tires, oil new and used chassis, his shop is located in St. Augustine. "Mikim Motorsports" like us on facebook to follow are racing efforts.