No drop in Luxeon module for the Solo/quest/Tec 20 that I know of. The only LED units available for these are the Matrix Module from Princeton Tec, and various PR-2 (3 volt) Nichia LED replacement bulbs.
The Matrix Module is a regulated 3 LED drop in unit that gives a runtime of up to 40 hours of constant light level from Alkalines, and 100+ hours on a pair of Lithium AAs (Eveready).
The Versalux PR-2 is a bit brighter, but cannot be used with Lithiums (overheat of LED).