(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.
- Locate the 8th digit of the VIN.
- 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 VIN | RPO Code | Displacement | Common Name |
|---|---|---|---|
| G | LS1 | 5.7L | LS1 |
| S | LS6 | 5.7L | LS6 |
Gen. 3 LS Truck Engines (Vortec)
| 8th Digit of VIN | RPO Code | Displacement | Common Name |
|---|---|---|---|
| Iron Block | |||
| V | LR4 | 4.8L | Vortec 4800 |
| T | LM7 | 5.3L | Vortec 5300 |
| Z | L59 | 5.3L | Vortec 5300 |
| U | LQ4 | 6.0L | Vortec 600 |
| N | LQ9 | 6.0L | Vortec H.O. 6000, VortecMax |
| Aluminum Block | |||
| P | LM4 | 5.3L | Vortec 5300 |
| B | L33 | 5.3L | Vortec H.O. 5300 |
Gen. 4 LS Car Engines
| 8th Digit of VIN | RPO Code | Displacement | Common Name (Notes) |
|---|---|---|---|
| C | LS4 | 5.3L | LS4 (FWD Only) |
| U | LS2 | 6.0L | LS2 |
| Y | L76 | 6.0L | L76 |
| 2 | L77 | 6.0L | L77 |
| W | LS3 | 6.2L | LS3 |
| J | L99 | 6.2L | L99 |
| P | LSA | 6.2L | LSA (Supercharged) |
| T | LS9 | 6.2L | LS9 (Supercharged) |
| E | LS7 | 7.0L | LS7 |
Gen. 4 LS Truck Engines (Vortec)
| 8th Digit of VIN | RPO Code | Displacement | Common Name |
|---|---|---|---|
| Iron Block | |||
| C | LY2 | 4.8L | Vortec 4800 |
| A | L20 | 4.8L | Vortec 4800 |
| J | LY5 | 5.3L | Vortec 5300 |
| 0 (zero) | LMG | 5.3L | Vortec 5300 |
| 4 | LMF | 5.3L | Vortec 5300 |
| K | LY6 | 6.0L | Vortec 6000 |
| G | L96 | 6.0L | Vortec 6000 |
| Aluminum Block | |||
| M | LH6 | 5.3L | Vortec 5300 |
| 3 | LC9 | 5.3L | Vortec 5300 |
| L | LH8 | 5.3L | Vortec 5300 |
| P | LH9 | 5.3L | Vortec 5300 |
| H | LS2 | 6.0L | LS2 |
| Y | L76 | 6.0L | VortecMax |
| 5 | LFA | 6.0L | Vortec 6000 (Hybrid) |
| J | LZ1 | 6.0L | Vortec 6000 (Hybrid) |
| 8 | L92 | 6.2L | Vortec 6200 |
| 2 | L9H | 6.2L | Vortec 6200 |
| F | L94 | 6.2L | Vortec 6200 |
…
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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.