Special Service Package, municipal

Years 2007–09, 2023–25 Models 2 Factory citations 5

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Also described as Vehicle special service, municipal

Also documented for Cadillac Chevrolet

Documented applications

Sierra — T1XX (2019–2026)

2023–2025 Factory-verified

the 2024–2025 lists print its contents under the code (high-capacity air cleaner, 220 amp generator, headlamp flasher, taillamp flasher calibrations, 110 volt instrument panel outlet, hitch guidelines, heavy-duty trailering provisions)

GM factory document — 2023 gmc 23 sierra 1500 electrical body builder sm en us 2022oct12, p.9.
GM factory document — 2024 gmc 24 sierra 1500 sm electrical body builder esid 23dec12, p.10.
GM factory document — 2025 gmc my25 sierra 1500 electrical bbm, p.8.

Yukon — GMT900 (2007–2014)

2007–2009 Factory-verified

The 2009 list words it as sales package, special service, municipal.

GM factory document — 2007 gmc yukon 2wd rpo code list, p.1.
GM factory document — 2009 gmc yukon 2wd rpo code list, p.1.

This page aggregates every documented appearance of 5W4 in the GMC reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.