95 Ford Explorer will not shift into reverse or neutral. all other gears work. on 1995 Ford Explorer

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The SUV has 260,xxx miles, runs fair for it's age and lack of upkeep prior to buying it. O/D light flashes at startup, and the SUV will not shift into Neutral or Reverse. Drive and all other gears work fairly well, there is some grinding if the weather is cold or accelerating too quickly. Some please help, it's the only vehicle I own with heat/air, and I have three kids, lol.
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Does it have park? The shift cable may have come out of adjustment. OD light flashing indicates a trans problem has been detected. Fluid up and clean ( pink ) or brownish with a burnt oder?
Park, Drive, and low gears all work correctly minus some shifting issue when cold or when accelerating too quickly. I have checked the trans fluid levels, which are fine. I'm sure it could use a flush though. Other than the shift cable, what else could be wrong. I'm doing everything I can to avoid replacing the whole transmission.