LS Engines

How to Identify an LS Engine

 
GM LS Engine

(Image/Super Chevy)

Before you begin your engine project, you need to know exactly what you have—and when it comes to General Motors’ 3rd and 4th generation LS small blocks, that may not be an easy question to answer.

How Do I Know Which LS Engine I Have?

There are more than 40 variations, including the LS-based Vortec truck engines.

The similarities between them make several LS parts interchangeable, but there are critical differences too. To ensure you’re using the the right parts, you need to know which LS engine you’re starting with.

There are two easy ways:

1. The 8th digit of the VIN

2. By visual inspection

The easiest way to tell the difference is to check the 8th digit of the Vehicle Identification Number (VIN) on the original vehicle. (See below.)

If you don’t have the VIN, you can still identify the engine by visual inspection if you know what to look for. The LS experts at Summit Racing created an interactive tool to help you easily make a positive ID by answering a few questions.

Check out the interactive tool here

Just answer a few basic questions and the tool will be able to tell you what LS engine you have (or at least really narrow down your options).

Please note that this guide is intended for stock engines. If the engine you are looking at has been modified, the guide may not give you the right answer.

How to ID an LS Engine by VIN

Chevrolet’s LS and LS-based Gen III and Gen IV small-block engines are generally known by their RPO code. You can determine the RPO code if you have the VIN from the original vehicle.

  1. Locate the 8th digit of the VIN.
  2. Consult the tables below to identify your engine.

[NOTE: Take care not to confuse the letter “B” and the number “8,” or the letter “O” with the number “0.”]

Gen. 3 LS Car Engines

8th Digit of VINRPO CodeDisplacementCommon Name
GLS15.7LLS1
SLS65.7LLS6

Gen. 3 LS Truck Engines (Vortec)

8th Digit of VINRPO CodeDisplacementCommon Name
Iron Block
VLR44.8LVortec 4800
TLM75.3LVortec 5300
ZL595.3LVortec 5300
ULQ46.0LVortec 600
NLQ96.0LVortec H.O. 6000, VortecMax
Aluminum Block
PLM45.3LVortec 5300
BL335.3LVortec H.O. 5300

Gen. 4 LS Car Engines

8th Digit of VINRPO CodeDisplacementCommon Name (Notes)
CLS45.3LLS4 (FWD Only)
ULS26.0LLS2
YL766.0LL76
2L776.0LL77
WLS36.2LLS3
JL996.2LL99
PLSA6.2LLSA (Supercharged)
TLS96.2LLS9 (Supercharged)
ELS77.0LLS7

Gen. 4 LS Truck Engines (Vortec)

8th Digit of VINRPO CodeDisplacementCommon Name
Iron Block
CLY24.8LVortec 4800
AL204.8LVortec 4800
JLY55.3LVortec 5300
0 (zero)LMG5.3LVortec 5300
4LMF5.3LVortec 5300
KLY66.0LVortec 6000
GL966.0LVortec 6000
Aluminum Block
MLH65.3LVortec 5300
3LC95.3LVortec 5300
LLH85.3LVortec 5300
PLH95.3LVortec 5300
HLS26.0LLS2
YL766.0LVortecMax
5LFA6.0LVortec 6000 (Hybrid)
JLZ16.0LVortec 6000 (Hybrid)
8L926.2LVortec 6200
2L9H6.2LVortec 6200
FL946.2LVortec 6200

You May Also Want to Read:

LS Engine Spotter’s Guide, Part 1: Matching the Vehicle to the Engine

LS Engine Spotter’s Guide, Part 2: Matching the Engine to the Vehicle

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7 Comments

  1. Pingback: LS Engine Spotter's Guide, Part 1: Matching the Vehicle to the Engine - OnAllCylinders

  2. Pingback: LS Engine Spotter's Guide, Part 2: Matching the Engine to the Vehicle - OnAllCylinders

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  6. Will 2008 LC9 Drop in 2007 GMC pickup with LH6 engine

    • Externally, most LS engine blocks (regardless of displacement) are darn-near identical save for engine accessory configurations and different intake manifold designs. So physically yes, it should fit in the engine bay without significant issue. The LC9 should also mate to your transmission, as all LS engines share identical output shafts and crank flanges.

      You’re also in luck that your truck was a 2007 model, as that means you had the later version of the LH6 engine that shares a 58X reluctor wheel and the E38-style computer with the LC9.

      Summit Racing’s LH6 Spec Guide and LC9 Spec Guide are good resources to bookmark.

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