Mirrors, outside, vertical trailering, power-adjustable with heated and auto-dimming upper glass, lower convex mirrors, turn signal indicators, puddle lamps, perimeter lighting (U12), auxiliary lighting, power folding and manual extending (extends 3.31 inch [84.25 mm]), black

Years 2025–27 Models 1 Factory citations 6

Also documented for Chevrolet

Documented applications

Sierra HD — T1XX (2020–2027)

2025–2027 Factory-verified

the 2027 lists omit the U12 reference; Pro, SLE: O; SLT, AT4, AT4X, Denali, Denali Ultimate: not offered

GM factory document — 2025 gmc sierra 2500 hd retail and fleet fleet order guide rpo codes, p.1.
GM factory document — 2026 gmc sierra 2500 hd retail and fleet fleet order guide rpo codes, p.1.
GM factory document — 2027 gmc sierra 2500 hd retail and fleet fleet order guide rpo codes, p.1.
GM factory document — 2025 gmc sierra 2500 hd retail and fleet fleet order guide, p.32.
GM factory document — 2026 gmc sierra 2500 hd retail and fleet fleet order guide, p.30.
GM factory document — 2027 gmc sierra 2500 hd retail and fleet fleet order guide, p.30.

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