Mitsubishi Repair: 1991 Galant Automatic Transmission, transmission specialist, valve body

Question
My '91 Galant is a pleasure to drive but recently after a 150km drive the 2 and the L gears disappeared. Only D gear and R gear is working. How did this happen? Short of changing transmissions, what can be done to fix the problem.

Answer
Danny,
The problem you're describing does not sound like an easy fix.  You may not necessarily need new transmission, but you need to have it serviced by a professional.  Your local mechanic may not be sufficient enough to fix this problem.  Make sure you take your car to a transmission specialist garage.  The garage that only service transmissions are the best.  The dealership is good as well, but they would be the most expensive.  It sounds like you may have a stuck valve body, bad front/rear clutch, or piston.  You may even need your manual linkage adjusted.  But only a professional can determine this.

I don't really have a solid answer as to how this could have happened.  Usually, transmissions can fail when the transmission fluid and fluid filter is not changed on a regular basis; usually every 30k-40k miles.
Good luck!