Head: Mercer 87
Chest: Law 87
Arms: Duke 92
Waist: Gung-Ho 92
Thighs: Gung-Ho 92
Lower Legs: Duke 84

Accessories:
Rifle: Shockwave 92
Pistol: Mutt 92

Duke, more than any other character, got screwed as far as his figures were concerned. The 84 version had that goofy grin, the 92 version didn't seem particularly sergeant-like, and the 93 version looked like the most indistinguishable trooper in the entire line. Let's not discuss the 97 version. I actually based this figure on the rendition of Duke from the comic that comes with the 2002 figures. I'm really happy with the way the head turned out: I don't get a Mercer feel from it at all. Of course, i'm biased.