Professional™ Rear Driver or Passenger Side Non-Adjustable Strut (503-280) by ACDelco®. Quantity: 1 per Pack. ACDelco Professional Premium Gas-Charged Shocks offer the superior ride of a Premium Gas-Charged Shock with patented RoadResponse™ technology. Custom-tuned gas charge for optimized vehicle performance, and also feature a hardened, chromed piston rod that provides an ultra-smooth corrosion- and scratch-resistant surface, increasing seal life.