Hi, my knowledge is pretty limited, but I understand that the series II involved the next generation changes including a firing pin brake. Also I believe they all are special editions from the Kimber Custom Shop. There weren't very many of them made (Only 600 of the Ultra CDP Elite II and 650 of the Ultra CDP Elite STS II). Both were produced in 2002. I saw something about a new STS barrel, don't know what that means tho. I got this info from the Kimber Shop page and I pasted the two paragraphs about our handguns. Sorry I can't be a better resource, but maybe those pages may help. I do know, as you do, that the Ultra CDP is an extremely comfortable weapon and it makes me look like a better shooter than I am. Won't be selling it any time soon, although I'm selling the Team Match.

Bob
http://www.kimberamerica.com/specialrun.php


ULTRA CDP ELITE II (2002): 600 produced. The first Kimber .45 ACP pistols with ramped match grade barrels. Black anodized aluminum frame, black oxide carbon steel slide, 3” barrel, carry melt treatment for rounded and blended edges, Meprolight 3-dot tritium night sights, 30 LPI checkering on front strap and under trigger guard, ambidextrous thumb safety and charcoal/ruby laminated logo grips. 25 oz. MSR: $1216

ULTRA CDP ELITE STS II (2002): 650 produced. The first Kimber .45 ACP pistols with ramped match grade barrels. Silver anodized aluminum frame, satin stainless steel slide. 3” barrel, carry melt treatment for rounded and blended edges, Meprolight 3-dot tritium night sights, 30 LPI checkering on front strap and under trigger guard, ambidextrous thumb safety and charcoal/ruby laminated logo grips. 25 oz. MSR: $1155.