Can you tell the difference? Most alternators look nearly the same, and that is why what is on the inside is so critical. Reliability starts with how it is made. Choosing PROFORM means choosing alternators with components produced by highly specialized machines, assembled by highly trained personnel using dedicated jigs and equipment, with everything 100 percent new for maximum longevity and optimum performance. After assembly each alternator is individually tested at the factory. Finally, it is boxed with a quality assurance graph that documents the specific units output performance. We do the testing, not you! And PROFORM proves it! Sold individually.