My 1993 Trek 5900 was the flagship model for that year and carried a mishmash of parts. Whichever was lightest went on the bike: some Dura Ace drivetrain stuff but downtube rather than integrated shifters to save weight; Dia Comp brakes; White Industries titanium BB; Chris King titanium headset; Ibis titanium threadless stem, one of those odd duck 1" things that superficially resembled a quill stem. Looks like Trek went for minimum weight first, with price only a secondary consideration, and no regard to group marque.
Pretty much the same way hill climb specialists approach their own custom builds.