MKM ✓ Factory-verified

GMC · Regular Production Option

Transmission, Allison 10 speed automatic

Years 2024–27 Models 1 Factory citations 6

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Also documented for Chevrolet

Documented applications

Sierra HD — T1XX (2020–2027) →

• 2024–2027 ✓ Factory-verified

  the 2026 guides print it without Allison; 2024: GM Authority 2024 Sierra HD page lists MKM as the 10 speed automatic with the 6.6L gasoline V8; Pro, SLE, SLT, AT4, AT4X, Denali: S; 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.12.

  ⛭ GM factory document — 2026 gmc sierra 2500 hd retail and fleet fleet order guide, p.11.

  ⛭ GM factory document — 2027 gmc sierra 2500 hd retail and fleet fleet order guide, p.9.

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