The one everybody wants

The LBZ ran barely two model years before emissions equipment arrived with the LMM, which is why it commands a premium and why so many are heavily modified. These trucks tend to be built rather than merely used.

That matters for charging. A built LBZ often carries added lighting, a winch, an inverter, upgraded cooling, gauges and an audio system, and frequently a rear or auxiliary battery on top of the factory pair. All of that draw sits on an alternator specified for a stock truck in 2006.

Finish matters on these trucks

Because LBZ engine bays are often detailed, billet and anodized housings are more popular here than on working trucks. Black, red, blue, polished and machined are all available.

Large case, not the gas truck unit

The LBZ uses the large case Duramax alternator, physically different from the gas truck unit of the same era. Order the Duramax-specific part.

Dual batteries

Replace both at once and match them. If you are adding a third battery for audio or accessories, add charging capacity first — a third battery without more alternator just moves the bottleneck.

Don't skip the wiring

See our Big 3 wiring upgrade guide.

Compare the LLY and LMM, or browse all Duramax alternators.