WEST MEMPHIS, Ark. — official release — Scott Frazier photo — Sam Hafertepe Jr. raced to his third Lucas Oil American Sprint Car Series victory of the season in the inaugural Mid-South Showdown Thursday night at Riverside Int’l Speedway. After losing legendary driver Shorty Chambliss on Monday, the feature was extended to 40 laps in honor of Chambliss’ signature No. …