When the gang at William Morris Agency sold their headquarters last week for $143 million, stunned real-estate observers wondered how the agency could command such lucre near the bottom of the market. However, a new picture finally reveals WMA's secret bargaining chip: the parking-lot gas pump where agents seek refuge from the retail class.Moreover, this is the fabled pump where some of Hollywood's most influential service-station attendants got their starts before moving on to Chevron, 76, Mobil and elsewhere. The opportunity to own a piece of history proved too irresistible for the building's buyers, whose previous attempt to buy an old agency headquarters fell through when CAA insisted on moving its 96-Octane Baby Mulcher and Stem-Cell Refinery to the Death Star in 2006. If this isn't the definition of a win-win situation, then we don't know what is.