Mechman high output alternators · Authorized dealer

GMC S-15 High Output Alternators

The GMC S-15 is the compact pickup people keep for decades: a hauler for the dump run, a commuter, a first truck handed down. Keeping it on the road means a charging system that can handle whatever got added along the way. This page lists every GMC S-15 high output alternator Mechman offers for 1988-1995 4.3L trucks and 1994-2003 2.2L trucks.

  • 20 products
  • 1988–2003
  • 170–400 Amp
  • Billet options
All GMC alternators

20 products

A Practical Upgrade for a Working Pickup

Most S-15s are not show trucks. They carry tools, tow a small utility trailer and wear a set of work lights. Add a better stereo for the commute and the original charging system starts to struggle at idle. A GMC S-15 high output alternator restores headroom without turning the truck into a project.

Choose your year and engine in the finder above and your truck lands in one of two groups. The 4.3L V6 from 1988 to 1995 uses one alternator family. The 2.2L four-cylinder from 1994 to 2003 uses a dedicated unit. Match your engine first, because the two take different alternators.

How Much Output You Need

Mechman high output alternators for the S-15 are listed at 170, 240, 250, 320, 370 and 400 Amp. For most owners, the lower end is the right call.

  • 170 Amp: a work truck with a few lights and a replacement head unit.
  • 240 or 250 Amp: one amplifier, a light bar and a trailer.
  • 320 or 370 Amp: an inverter for corded tools, or several amplifiers.
  • 400 Amp: a full audio build in a small cab.

Both billet and standard cast housings are offered. Billet is machined from solid aluminum, with finishes including Red, Dark Blue and Chrome. Cast keeps the bay looking stock, which suits most S-15 owners. An S-15 high output alternator and a healthy battery work as a pair, so check our batteries if yours is getting old. Chevrolet's version of this truck has its own S-10 page, and Buick Roadmaster owners have a separate page that shares several of these units. The Chevrolet and GMC alternator collection covers more trucks.