Search by number: 2005 Audi S4 4.2L Alternator ProAmp 11211 $171.00 each OPTIONS: 190 Amp Watercooled Alt Hitachi Unit ProAmp 11158 $502.00 each OPTIONS: Watercooled Delphi Unit Why is there more than one unit for my car? Look at the TECH SPECS when more than one unit is shown for your car. AMPS (ELECTRIC CAPACITY): must match you vehicle electric requirements. *** Call us if you are looking to increase your unit capacity! OE ALTERNATOR MANUFACTURER: It is recommended to match the Make of your alternator