* Fuel Injection: The 1987 will have TBI, while the 1997 likely has sequential fuel injection (possibly even OBD-II). This means different wiring harnesses, computer modules (ECM), sensors, and fuel delivery systems.
* Emissions: The 1997's emissions standards are far stricter than those of 1987. Simply dropping in the older engine will likely fail emissions testing.
* Wiring Harness: The wiring harnesses are completely different.
* Computer Control: The 1997 engine management system is far more sophisticated.
* Accessories: The placement and type of accessories (alternator, power steering pump, etc.) may differ.
* Transmission: You'll need to consider compatibility with the transmission as well. While both might be automatic, there could be issues with compatibility.
While a 350 swap *is* possible, it would be a major undertaking requiring significant modification, custom fabrication, and potentially a complete engine harness swap (or even a stand-alone engine management system). It's far from a simple bolt-in affair. You'd be better off finding a later-model 350 that's more compatible with your 1997 Suburban.
