1997 will have sequential fuel injection, so there will be 8 wires from the computer, 1 for each cylinder's injectors.
Those are Ground wires.
Then there will be 1 Red wire that daisy chains from one fuel injector to the next.
That's the 12volt wire
So all the fuel injectors get 12volts when key is on, then computer Grounds each injector when it needs to release some fuel, which would follow the firing order.
But you should have the 1997 engine wiring harness and computer so it is pretty much plug and play for the engine stuff.
The interface to the power systems and dash will be the challenge
Some good reading here on that:
http://www.therangerstation.com/tech_library/index-conversions.shtml