05 Specialized Epic Comp rear brain shock question. Please help out a newbie!

[Brewcity]

Hey guys...a newbie here that needs some help.
I have searched this forum (which is great!), and others, and cannot for the life of me, find out what I can do about my rear shock (Fox Float R Brain Lite...seen here:

I have an 05 Specialized Epic Comp (bought from a friend recently)...and I just want to know if there is a different company that makes a rear shock that will fit my 05 Epic, or if I need to get it serviced.
I don't think anything is wrong with it just yet (only rode it 4 times since getting it)...but I know, with it being an older bike, that it will fail at one point, and I want to be ready when that happens.
Can anyone please let me know if they have replaced it with a different shock, and if so, which one? Or...if it needs to be serviced, how much it will likely cost.
Thank you guys SOOOOO very much. I really do appreciate it.

BTW..what does 11.7X1.875 mean? This is the measurement of the rear shock on the Specialized website. Just trying to learn...so thank you for the help!