The rectifier is the most common cause of alternator failure. With two rectifiers it doubles their durability. 
If you are using your alternator to it's extreme, 
YOU MUST HAVE THIS ALTERNATOR!

Offered in 140, 170, 200 and now!, 250 amp versions with many different front housing mounting configurations for a direct fit in your GM vehicle or adaptive fit to many vehicle types. We have helped with many adaptive applications like Busses, Porsche's, Boats, Fords and many others.

Alternators produce AC current, just like the current from your house wall outlet. Then it uses a bridge rectifier, typically with 6 diodes, to convert the AC current to DC to send to the battery. With Dual Rectifiers, you get 12 Diodes, which spreads the current load over a much larger area making the alternator twice as durable and twice as efficient at converting the AC current it makes to DC.  The many benefits include: less heat build up, less current loss, higher amperage output when hot, more power at idle. Plus, the service duty and life increases substantially. When the rectifier heats up the diodes won't pass as much amperage through them, therefore, the amperage output drops. With our double rectifier alternator you have twice the amperage carrying capacity and double the cooling surface area to keep the diodes cool. This all adds up to......
MORE POWER, LESS HEAT PROBLEMS and GREATER RELIABILITY.

Direct fit to the following popular Lester numbers: 7802, 7861, 7864, 7894, 7901, 7918, 7921, 7977, 8103, 8112, 8160, 8163, 8165, 8172, 8173, 8203, 8206, 8216, 8219, 8221, 8227, 8231