I got this reply from GM:
Mr. Djurre Gerritsen ,
Per your inquiry on color for your '03 Avalanche, below is the information you requested:
Interior color is 692 - DARK CHARCOAL
Exterior color is 91U - ARRIVAL BLUE METALLIC
Your local Chevy Dealer can help you order any replacement parts you may need.
Thanks.
John Schwegman