UNL ✓ Factory-verified

Chevrolet · Regular Production Option

Auxiliary harness

Years 2025–26 Models 1 Factory citations 2

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Documented applications

Silverado Medium Duty (GM515, 2019–2026) →

• 2025–2026 ✓ Factory-verified
  ⛭ GM factory document — 2025 chevrolet silverado 4500 hd 5500 hd and 6500 hd fleet order guide rpo codes, p.1.

  ⛭ GM factory document — 2026 chevrolet silverado 4500 hd 5500 hd and 6500 hd fleet order guide rpo codes, p.1.

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