I've got an 06 Sierra 1500 that I've never been able to figure out the trim level on. I'm assuming it's an SL, but don't know how to verify. Manual seats, manual transfer case, power windows, power door locks, power mirrors. Not compatible with a remote for locking/unlocking (checked the glove box sticker). Is there a code on that sticker that will tell me what the trim level is, or can I look it up from the VIN somewhere?