For the better part of five decades, Tom Durant has been searching for the type of horse that could carry him to the top of the game--namely, the Kentucky Derby. With his homebred 'TDN Rising Star, presented by Hagyard' D'code (Speightstown), who makes his two-turn debut in his second career start in Friday's GIII Southwest Stakes, Durant is hoping that he has found such a star. An auto dealer from Texas, Durant got his start in the horse business when a customer talked him into buying a Quarter Horse broodmare....