[Q] UGJL2 modem on I9000XWJS3, how to do it?

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I just installed I9000XWJS3 on my I9000T however I lost 850 band, I would like to know if is it safe to install JL2 Modem found on this post http://forum.xda-developers.com/showthread.php?t=906977

They have note in there that reads

"NOTE: If you have a Bell i9000M, do the following to (hopefully) prevent your internal SD card from dying:
1. Upgrade to JL2 using either Kies (recommended) or Odin (make sure to check Bootloader Update)."

Do I have to check Bootloader Update option since mine is a I9000T?

Also when going to menu *#1234# I got this
PDA: I9000XWJS3
PHONE:I9000XXJPY
CSC: Unknown

How can I fix CSC? which one is compatible with my current device settings?

Thanks in advance