XRAY X4 58mm ECS Drive Shaft. This replacement driveshaft is intended for the XRAY X4. 58mm Front / 52mm Rear shafts are recommended for low-traction or tight asphalt tracks. When using the shorter 58mm Front / 52mm Rear driveshafts that create more steering and make the car more aggressive. Package includes one unassembled driveshaft.