(Image/LSX Magazine)
Before you begin your engine project, you need to know exactly what you have—and when it comes to General Motors’ Gen 5 LT small blocks, it’s currently a lot easier (especially with car engines) than it is to identify GM Gen 3 and Gen 4 LS small blocks.
How Do I Know Which LT Engine I Have?
There are currently just five LT engines, including the LT-based EcoTec3 truck engines: LT1, LT4, L83, L8B, and L86.
Much like with LS engines, the easiest way to be sure which LT engine you have is to check the 8th digit of the Vehicle Identification Number (VIN).
Consult these tables to identify your LT engine by VIN.
[NOTE: Take care not to confuse the letter “B” and the number “8″]
LT (Gen 5) Car Engines
| 8th Digit of VIN | RPO Code | Displacement | Common Name |
|---|---|---|---|
| 7 | LT1 | 6.2L | LT1 |
| 6 | LT4 | 6.2L | LT4 (supercharged) |
EcoTec3 Truck Engines
| 8th Digit of VIN | RPO Code | Displacement | Common Name |
|---|---|---|---|
| C | L83 | 5.3L | EcoTec3 5.3L |
| R | L8B | 5.3L | EcoTec3 5.3L (with eAssist) |
| J | L86 | 6.2L | EcoTec3 6.2L |
How do you verify visually that someone didn’t put a 5.3 in a truck that is supposed to have a l86? I bought a 2015 sierra denali which says it has a 6.2 but I know the engine was warranty replaced at some point and I want to make sure it has the correct engine. It doesn’t have the power I believe it should.
Anybody know about it? Does it has differneces in visual ?
Check the casting number of the cylinder head which is located just between the valve cover and the exhaust manifold on the passenger side on the side of the cylinder head. Should read 12685669.
I have a 2019 AT4 GMC Sierra. My 8th digit is L. What the heck???
I think the 2019+ 6.2 truck engine is known as the L87. Which is newer than this article.