* If both cars have the same engine: Then yes, it should fit. However, you'd still need to transfer all the associated components (wiring harness, computer, etc.).
* If the cars have *different* engines: It's much more complicated and likely won't be a straightforward swap. While the engine bay might be similar, the mounts, wiring harness, computer, and potentially even the transmission could be incompatible. You'd likely need significant modifications, potentially including custom engine mounts, new wiring, and a new ECU. This is a major undertaking.
To know for certain, you need to specify the *exact engine code* for both the Regal and the Park Avenue. The engine code (often a 3- or 4-letter code) is crucial for determining compatibility. You can usually find this on a sticker on the engine block itself or in the owner's manual.
