* Wiring Harness: The wiring harnesses are different. You'll likely need to use the 1990 harness with the 1987 engine, or adapt the 1987 harness to the 1990 system. This can be a complex undertaking.
* Computer (ECM): The Engine Control Module (ECM) is also different. You'll need the 1990 ECM to match the 1990 wiring harness. Using the wrong ECM will lead to drivability issues at best, and engine damage at worst.
* Sensors: While many sensors are similar, some might have different connectors or specifications. You might need to swap sensors or adapt connectors.
* Accessories: The accessories (alternator, power steering pump, etc.) should bolt up, but you might find minor differences in brackets or mounting points.
* Exhaust: The exhaust manifolds might need adjustment or replacement to fit the 1990 car.
In short, while the engine itself is mechanically similar, the swap is not a simple bolt-in affair. It requires a good understanding of automotive electrical systems and potentially some fabrication skills. It's not a project for beginners.
