Chevy Corvette featuring GM RPO codes to designate LS engine type, displacement, and more

RPO Codes: Everything You Need to Know for Your LS Swap


Not every LS based engine is a “Corvette motor”. As cool as that would be, the same parts that work on Corvette engines wouldn’t work on other engines. So to save everyone involved extra headaches and delays in your build, it’s best to know what you have so that you can formulate a game plan for the type of build you are wanting to do. RPO codes can help with that!


What are RPO Codes? Where Did They Come From?

RPO stands for Regular Production Option. RPO codes were created specifically by GM as a method of standard coding for vehicle configuration options in 1970 and are made up of a combination of three alphanumeric characters that refer to a specific option or modification to your vehicle. These codes give specific information about everything on your car from engine and transmission to interior and exterior trim styles and paint color.

The RPO codes for your vehicle are essentially the DNA of it. These codes designated how your vehicle was put together at the factory. From these codes, the plant would know which exact parts to either include or leave off of your specific model during assembly.

Check out our handy guide showing the RPO code of GM’s LS-based engines as well as some differences between them.

RPO codes spec sheet ICT Billet

How Can RPO Codes Assist in My LS Swap?

Locating your RPO codes in your donor vehicle is important when swapping out your car’s engine for the LS coming out of the donor car or truck. The RPO codes will help you decipher multiple pieces of vital information including the exact engine you have, how much power it has, and what parts you’ll need to make it work in your LS swap.

These RPO codes will be extremely beneficial in identifying multiple factors you’ll need to know for your swap. Specifically, information such as:

  • Engine displacement (ie: 4.8, 5.3, etc)
  • Block material (ie: iron or aluminum)
  • Type of differential (if limited slip or open diff)
  • Fuel type (flex fuel or not)

In our guide above, you can clearly see the differences in the graph to better understand how each engine varies.

Where Can I Find the RPO Codes for My Donor Car?

Back in the 1970s when GM first came out with RPO codes for their vehicles, they placed these codes in a laminated packet in the backend of their automobiles. Now, however, you’ll likely find the RPO codes located on a sticker in the glovebox of your donor vehicle.

Typically, these codes would be something a layman or woman would find utterly nonsensical by the looks of it. It’s simply a tag with three digit alphanumeric codes that tells you every build spec of the vehicle. While it’s not necessarily something you’d need to know for your everyday car, it will come in handy when doing an LS swap.

For clarity, your donor vehicle is what the LS engine is coming out of. This is the vehicle that’s donating the engine and drivetrain to put in your car, truck or SUV. If you want an aluminum 5.3, the RPO code will show an engine designation of LM7. This information will help you determine which brackets and accessories you can utilize for your swap.

GM RPO Code example

This image shows an example of what your RPO codes sticker will look like in your vehicle. Note that the section whited out at the top of the sticker would be where your VIN would be located.

Looking to do an LS or LT swap for your next project? Check out our LS and LT parts and accessories designed to make your swap seamless and as easy as possible! If you have questions about your swap or what you’ll need to make it the build of your dreams, contact us today! We’re happy to help!

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