Stainless steel 6062 cases were produced by Spillman Rolex's
link longtime supplier for steel
link Oyster cases. Gold
link cases were produced by Genex the case-making arm of famed bracelet maker Gay Frères which Rolex acquired in 1998 identifiable by the maker's mark 12 on the inside caseback. I've read one auction catalog that hinted at possible two-tone 6062s cases being produced but this remains a rumor.