1970-1988 GMC G2500 5.7L 12si 250-320amp High Output Alternator

Fitment:

This is a direct fit high-output alternator for the 1970-1988 GMC G2500 5.7L. Being a direct fit, this alternator fits directly into your stock alternator location.

Plug:

This high-output alternator comes with a separate adaptor plug. One side will plug directly into the aftermarket high-output alternator, and the other side will plug into the factory plug.

NOTE: If you require charging at a certain voltage setpoint, we offer a selection of different voltage regulators that you will need to purchase with the alternator for it to be installed. View our Regulator Options Here.

Pulley:

This alternator also comes with a smaller pulley, which causes it to spin faster than a larger pulley. This can help the alternator produce its maximum output. With a smaller pulley, it is required to install a 1/2" - 1" shorter belt.

See this Blog Article for assistance in finding the correct shorter belt.

Big 3 Wiring:

When Upgrading to a High-Output Alternator, it is required to upgrade your wiring with the Big 3 Wiring Upgrade Kit. It is recommended to use 1/0 100% copper wires for the upgrade. Our Big 3 Wiring Upgrade Kit is 10% off with a purchase of a JS Alternator; use code BIG3DISCOUNT at checkout.

Learn Why The Big 3 Wiring Upgrade Kit is Required for All High Output Alternators