I've never repaired bulbs, only clusters - interestingly the first time I did one, I obtained the exact right SM LED's from RS Components, which came in a large spool (FAR more than the handful I wanted), however, as it was for a Mercedes price wasn't an issue, and they weren't expensive any way. Every one I did after that used the exact same LED's, so the spool came in handy.
As I understand it?, more modern designs often use CAN bus or such, rather than simple 12V feeds as for a bulb.
Thinking on?, presumably all the ones I've changed have been for brake lights? - and presumably the LED's were red? - it was were I used to work, so I haven't seen them for a while now.