1 The S.Drive pulley system comes complete and ready to install. EMS even includes the A/C compressor, alternator, power steering pump, and water pump, but these are not cheapo parts. They are all sourced from reputable companies like Edelbrock, Powermaster, Gates, and Sanden. The EMS crew pre-assembles the alternator and power steering pump to make installation even easier. All the pulleys and brackets are CNC-machined from 6061-T6 aluminum.