I believe I have the only NOS set available literally in the world !
Took me 3 years to find them and I got them from a ex-Sega employee in th USA who had them brand new sitting in his office desk.

Cost me a ridiculous amount, but at the time I needed them for a second Viper Night Drivin machine. My brother didnt buy the 2nd Viper so I have the balls left over. When I bought my first Viper machine, it didnt have them, but luckily a guy in the USA was wrecking a Viper that was accidentally left outside during a business move and the machine got rained on and completely ruined cause the glass was off. I scored a set from that wreck which are now in my machine.

If anyone from AP buys a Viper Night Drivin without the balls and they have some $, I have a NOS set glow balls.