DARLINGTON, S.C. — Brad Keselowski provided perhaps the biggest throwback at the Southern 500 — giving Team Penske its first victory at Darlington Raceway in 43 years. Keselowski beat leader Kyle Larson out of the pits with 22 laps to go, then pulled away on the restart to sweep the weekend at Darlington. Keselowski took the Xfinity race Saturday when leaders Ross Chastain and Kevin Harvick wrecked late.