Code reads "incorrect gear ratio 3rd and 4th gears. Changed fluid, no change, speedo and tach work so I don't believe it's the Output Sensor. Someone mentioned it may be a broken 3rd or 4th gear hub internally. Anyone? May not have hope of an easy fix on this one.

Welcome to AF! Unfortunately you are now in the market for a new or rebuilt transmission. I had the same issue with a 97 T&C and ended up with a rebuilt transmission. Take the vehicle to a transmission shop and have them check it with a trans capable scanner that should give you more information.