On the RH tranny it's easy, you just trick the computer with a 1000 ohm resistor in place of the the sensor.
What makes the RH easy is the stock sensor is external, you just unplug the sender and short beween the connector wires with the resistor.
On a RE tranny, '96 and up, the sensor is internal to the trans.
You would have to find which two wires go to the sensor, cut them and install the resistor.
Not really all that much harder but I don't know which wire colors you would need to cut.
'95 2500 4wd auto
'95 3500 5 speed heavy hauler
Stock for one day