No. "Thunder" is LG's internal code name for the Optimus series of phones. ls670 is the specific model of "thunder" (aka optimus) you are running. Put that info together and it = You are running an LG Optimus S, code named ThunderC, model number ls670.
I'm interested in rooting and putting a rom on my phone, but I never done it before and I don't want to mess up my phone. I want one specifically cricket and prefet it to be 2.2. I got data and talk and txt, but no mms.