You'll need to determine the engine codes for both the donor (97 Caravan) and recipient (96 Voyager) vehicles. These codes are usually found on a sticker on the engine block itself, or in the vehicle's documentation.
* If both vehicles have the *same* engine code, then the engine is likely directly swappable, though professional installation is recommended.
* If the engine codes are *different* (even slightly different), compatibility becomes less certain. While some engines within the same generation might be adaptable with modifications (wiring harness, computer, etc.), others might be entirely incompatible due to differences in mounting points, sensors, or other critical components.
In short: You MUST identify the exact engine codes to determine compatibility. Without that information, a definitive answer is impossible. Contact a mechanic or parts specialist familiar with these vehicles for definitive guidance.