I have electrical items that are UL rated for class 1, div 2 a-d. I need them in an area that is class 1, div 2 group c. Can I just use any Nema 4x enclosure, or does my enclosure also have to be Class 1, div 2 group c rated?

Look in NFPA 70 NEC, "enclosures". Specifically, Article 500 describes the NEC Division classification system, while Articles 505 and 506 describe the NEC Zone classification system.