Are you installing the '89 to replace the 2004? Usually, folks do the opposite. If installing the newer motor, you should price new controls. I paid $130 for new Merc controls and wiring harness. It was plug and play.
The wiring for both motors is likely the same or real close, unless the Merc is EFI. However, I would expect you will need to have or make some sort of adaptor to connect the Merc harness to the Force harness.
On a related note, have you checked the compatibility of the mechanical part of the controls you want to use. Some motors have different "throw" for shift cables than others. Some push to close the throttle, like the Merc. Johnnyrudes push the throttle open. I have no idea what Force does.
If wanting to adapt the new control to the old motor. the simplest way is to cut both harnesses in the middle and use some butt splices to connect the wires. Both should use most of the standard wire colors. The Force has a hot light, and the Merc likely has a overheat buzzer. they likely interchange..
