Mitsubishi has changed a number of parts over time. This small and simple one can cause some grief when installing... The new style switches are actually used on a number of other Mitsubishi models, and they have crossed it over to the 3000GT and Stealth, though it does not seem to be as direct a cross over as we would like. The new switch does not come with a pigtail harness on it, so there is no extended wires.
At first glance when installing, you might remove the old switch and see that it has 2 wires attached with a screw to the end of the switch. Well, pull long enough on the wires and there is a release harness tucked up in there that will emerge, simplifying the process. Unplug that harness and remove the old switch. Unfortunately, the new switch does not directly/easily fit onto the harness - you have to tweak it a little. Using a razor or exacto knife, shave off the little pointed tabs on the sides of the harness so it will slide into the new switch. Press them together and screw the switch back into the door jam.
"Wash rinse repeat" for the other side if you bought two switches.
NOTE: Mitsubishi has changed this number before. The pictures below represent 1st gen cars (1991-1993). Later years may vary yet again.
NOTE2: If the harness pictured refuses to pull out through the hole, you may have to resort to cutting the old switch out and using a couple crimp-on butt connectors to get the new switch hooked up.