Possible causes? The odometer does not change either.

Is there a sensor on the transmission somewhere? It is an automatic.

If the Ram speedometers are anything like the Neons of that era, they had a problem with cold solder joints in the speedometers. I've had 2 instrument panels in my '98 Neon and both had this problem. Both the speedometer and odometer worked intermittently, then not at all. For the Neon, after pulling the instrument panel, you can touch up the solder joints on the circuit board where the speedometer is connected, and it starts working again. If I looked at these solder joints (before touching up), it looked like there was a small circular crack in the solder around the post in the joint. I needed my reading glasses to see the cracks. This may or may not be a problem with the Rams, but since they come from the same era, it might be worth looking at.

Could be either the rear speed sensor or the transission speed sensor.

Thanks guys.

If I pull the sensors for inspection, should I drain the fluid first?

My 99 Ram had the same symptom and the ABS light also came on. Mine had a bad speed sensor in the rear axle housing. Easy to fix. Same thing happened on my '00 Chrysler but this one was on the trans. Even easier fix.

I agree the Neons had a speedo problem that wasn't a speed sensor. It was also intermittent. My mother had one that did this. When I gave the car to a friend he found the fix online and repaired it rather quickly and now it's fine.

9 out of 10 times, it the sensor on the rear diff, corrosion, road salt usually kills the unit,.....the tranny unit is mounted on the passenger side of the tranny case