"Also, as far as the gauges being stuck, you can pull the dash out and remove the bezel. Then put a little penetrating oil at the base of the needle and slowly move the needle back and forth several times. Many people have freed them up this way.
As I recall there are 3 tabs on top of the dash and lift the cluster straight up. Unplug the elwctrical harness and then take it to a bench and lay ot face down. Remove the phillips screws on the back side (cant remember if it was 6 or 8 of them) and lift the plexiglass off the gauge cluster. Many have had to do this."
I have done it several times and I can tell you that it is not Plexiglas but actual glass. I've broken two so that's how I know. I do use Plexiglas to replace the broken glass pieces though. Before you go to all that trouble take a cheap, free at Harbor Freight, volt/ohm meter and unplug the wire/wires to the thermocouple that sends the signal to the temp gauge and remove the sender. With a heat gun or hair dryer put the two probes on the connector and the body of the sender. Set the gauge to ohms and before you apply the heat it should read one ohm. As the dryer gets hotter on the tip of the sender the ohms will begin to fall indicating that the sender is working. If it doesn't work then you can start with the sender first and that might just do it. I had the needle on my temp gauge fall off inside the cluster so I had to take the glass out. JD did not want us to work on these clusters. The one on my X485 is no better but has 8 little prongs that hold the glass in instead of glue so it's a little easier.