Its usually under a flip-up plastic cover like the outside outlet and there's usually a sticker (unless the previous owner removed it). It would be very unusual if you didn't have one. I think the entertainment center is in the slide beside the fridge on that model... look on the outside wall of the slide.
2015 Rockwood Signature UltraLite 8282WS Platinum, GY Marathon LRD, TST 507RV TPMS
2005 GMC 2500HD CCSB D/A, Curt E16, Prodigy P2, Garmin RV760LMT w/BC-20 b/u cam