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What year did the LQ4/LQ9 become Gen IV?

Neither did. The LQ4 (1999–2008) and LQ9 (2002–2007) are both Gen III, 24x engines. GM's Gen IV iron-block 6.0 truck engines are the LY6 (2007–2013) and L96 (2010–2020), which use rectangle-port heads and VVT. The Gen III and Gen IV trucks overlap around 2007–2008, so confirm with the RPO sticker and VIN rather than the model year.

Last updated

What we recommend

They never did; the LQ4 and LQ9 stayed Gen III. In 2007, carryover GMT800 trucks could still have Gen III LQ4/LQ9 engines, while the new GMT900 trucks got Gen IV engines: the LY6 replaced the LQ4 and the L76 replaced the LQ9. If you see VVT, a front cam sensor and side-mounted knock sensors, you're looking at Gen IV, not an LQ4/LQ9.

Check this first:

  • Look for VVT, a front cam sensor and external knock sensors to identify Gen IV

Based on what we've seen work across our own builds, our friends' builds and the wider LS community, reviewed by our lead shop tuner (over 20 years of LS and LT tuning experience). Every combination is different, so use at your own risk.

Go deeper

Check this first

  1. Look for VVT, a front cam sensor and external knock sensors to identify Gen IV

Try this, then this

  1. Check for VVT solenoid/front cover and knock sensor bosses — instant Gen IV tell. Worked if: generation confirmed

How you know it's fixed

  • Engine identified as Gen III LQ4/LQ9 or Gen IV LY6/L76

Still not fixed?

  • If it has VVT/front cam sensor/side knock sensors, it's Gen IV - order Gen IV parts

Key numbers

WhatValue
LY6 replaces LQ4Gen IV 6.0 with VVT, rect-port heads
L76 replaces LQ9Gen IV aluminum 6.0

Time and cost: Visual inspection

What engine is a 6.0L with a 'K' VIN code in a 2008 GM van?
What we recommend

A 6.0L with a K VIN code in a 2008 GM van is the LY6, a Gen IV 6.0 with VVT and rectangular-port (L92-style) heads. Cathedral-port intakes won't bolt to those rectangular-port heads without an adapter, so we recommend planning the whole top end together. It's also a 58x VVT engine, so it won't drop straight into a Gen III electronics setup without conversion parts.

Check this first:

  • Intake port style matches the heads
  • Your ECU and harness support 58x and VVT, or budget for conversion parts

Check this first

  1. Rectangular ports + VVT + front cam sensor = LY6

Try this, then this

  1. Check ports, VVT, and cam sensor location together — all three confirm Gen IV. Worked if: all agree

How you know it's fixed

  • LY6 confirmed

Key numbers

WhatValue
LY6 portsrectangular port heads

Time and cost: Visual inspection

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