You have something called an integration relay that controls most of the indicators on the gauge cluster. Did you check the bulb - was the original one burned out? On the poweron self test - did you notice any indicators that did not come on, like Dave suggested?
Make sure the easy stuff is checked off first - double check all fuses and bulbs - even having a blown fuse or bulb from a separate circuit can have weird results in others. Check all traces going to the lamps on the cluster - all oxidation on the terminals might cause a bad or intermittent connection. This is particularly true if you go mudding with the truck - even if you are careful, moisture and dirt can get everywhere.
This might require some back tracing of wires to their sensor or switch - could be the wire along the way has shorted agains the chassis or completely worn through - they do make signal injectors that run a high frequency signal in the line that can be picked up by a reciever keyed to the frequency - but simple hand tracing of wires can yield just a good a result as well as provide you with a visual inspection of the wire\'s insulation.
In any case, finding the wiring issue is tough, lots of work and eliminating other sources of failure can take some time. Good luck.