* Engine Code: The critical factor is the *specific engine code*. While both are 1.9L DOHC, there might be subtle internal differences between the 1997 and 1999 engines. These differences could affect things like bolt patterns, sensor locations, and even the transmission interface. You need to verify the engine codes are identical or very closely compatible.
* Transmission Compatibility: Although both have automatic transmissions, the transmission itself might have slight variations between model years that could impact compatibility with the engine. Again, verification is key.
* Wiring Harness and Computer: The engine control module (ECM) and wiring harness are also crucial. A 1999 engine may have different sensors or wiring configurations than a 1997, potentially causing issues even if the engine itself is mechanically compatible. You'd likely need to use the 1999 harness and ECM.
* Mounting Points: While unlikely, minor variations in mounting points between the engine blocks are possible.
In short: You need to get the engine codes from both engines and compare them carefully. Ideally, find the same engine code from a parts database to confirm compatibility. Even then, you should consult a mechanic experienced with Saturns to assess the feasibility and potential challenges of the swap. Just because they're both 1.9L DOHC doesn't automatically guarantee a direct swap. There's a good chance it'll work, but some adaptations might be necessary.
