* Electronics: The 2003 engine will have a much more sophisticated engine control module (ECM) and wiring harness. The 1995 system won't be compatible. This is the biggest hurdle.
* Sensors and accessories: The placement and types of sensors, as well as the alternator, power steering pump, and other accessories, may differ. You'll likely need to adapt or replace many components.
* Mounting points: While the overall dimensions might be similar, subtle differences in mounting points and brackets could cause problems.
* Transmission: The transmission compatibility depends on the specific transmission in both cars. While it *might* be the same, it's not guaranteed.
In short, while it's *theoretically* possible with significant modification and custom fabrication, it's not a practical swap for the average enthusiast. The cost and time involved in making it work would likely far outweigh the benefits. Finding a used 1995 3.8L engine would be a much more straightforward and cost-effective solution.
