How do I find my RPO code?

The RPO code is on GM's option sticker in the glove box. It's a grid of three-character codes; the engine code is one of them (e.g., LM7, LQ4, L33, LS1). Match it against our engine table.

The 8th character of the VIN also identifies the engine, but GM used different letters on cars, trucks and SUVs for the same engine, so use the VIN to narrow it down and the RPO sticker to confirm.