You probably already found this, but in case not, Rockshox has a site here: https://trailhead.rockshox.com/en/search/ that you can search by your fork serial number to get exactly which model it is (not just the name Sid, but an alphanumeric designation indicating the model years). The rebuild kits usually have a list of those alphanumeric designations so you can match to your fork and not rely on knowing the exact year of the bike. For example, I believe the current iteration of the Reba RL is "A8".