??? I pulled up my 1980-1989 Ford Truck Master Part diagrams, as I did not recognize the type of transmission. The 92 is the same generation as the 89, so this list often helps for the 90-91-92 also. Then it dawned that you were talking of the Mitsubishi. A quick google confirmed it, and that it was used on 89-92.
OK!! THREE plugs. One plug set is for the backup lights, the other for the neutral safety switch, one for speed sensor (on some models).
The back-up light switch is two wire, purple w/orange stripe and black w/pink stripe (89), left side of trans, roughly the middle.
Neutral safety switch is black and black w/white stripe (89). The diagram is fuzzy on actual location, apparently on top of the trans. right side of the trans, in the top cover, next to the shifter.
The speed sensor is usually located on the tail of the t-case, I do not have any wire color codes for it.
Hope it helps.
Librum.