The SAE number I remember for the bulbs, is 194 there are other numbers for the same bulb .
The GEN bulb is the same as all the other bulbs .
I changed to LED replacement bulbs about June of last year, word of caution, these LED bulbs have the wire leads fold over the end of the bulb instead of staying on one side, you need to put the wire on one side I used a small pair of pliers and twisted the lead into a circle didn't need to cut it, it will fry the circuit board on the tachometer if you don't do this, the speedometer does not have this issue with the different bulb holder that is used there .
Also if you use an LED for the GEN light you need to add a resistor in the circuit otherwise the alternator will not work, it needs an incandescent bulb, or an added resistor to get electrical generation initiated on start up .
I do a lot of night riding and the LED's improved instrument visibility to my old eyes !!!
http://www.bmwr65.org/YaBB2.612/cgi-bin/yabb2/YaBB.pl?action=downloadfile;file=Webp%5Fnet%2Dcompress%2Dimage%2EjpgHere's a link to a BMW tech site, it describes the GEN light circuit in "painful detail" .
https://bmwmotorcycletech.info/genlampresistor.htm
