BL4 ✓ Factory-verified

GMC · Regular Production Option

Label, price, refer to geographic chart

Years 2006–07 Models 2 Factory citations 4

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Also documented for Chevrolet

Documented applications

Sierra — GMT800 (1999–2007) →

• 2006–2007 ✓ Factory-verified internal

  only in: heavy-duty models (GM’s HD list: 1500HD, 2500HD, 3500)

  ⛭ GM factory document — 2006 gmc gmc c sierra 2wd rpo code list, p.1.

  ⛭ GM factory document — 2007 gmc sierra classic 2wd rpo code list, p.1.

Sierra HD — GMT800 (2001–2007) →

• 2006–2007 ✓ Factory-verified internal
  ⛭ GM factory document — 2006 gmc gmc c sierra 2wd rpo code list, p.1.

  ⛭ GM factory document — 2007 gmc sierra classic 2wd rpo code list, p.1.

This page aggregates every documented appearance of BL4 in the GMC reference. Confidence and citations are shown per application — the same code can be better documented in one year than another.