It sounds like all 3 problems started at 3 different times, correct?
 If so, they're all probably unrelated and just happen to involve the cluster. First
thing to do is check and clean the connections on the back of the cluster, just in
case. Next, get an EVTM or Ford Service CD for your truck off of Ebay. They're cheap
and you need to have one to properly work on your truck.

 1. Temp gauge. Locate the temp gauge sender on the engine. IIRC it's next to the
thermostat housing. Disconnect and ground the wire going to it. The gauge should read
full scale. If so you have a faulty sender or the engine thermostat is stuck open.
(Just replace both. At this point you're long overdue for a new 'stat anyway). If it
doesn't read full scale, the likely culprit is the gauge.

2. Fuel gauge. Same test, same results. The connector for the sender at the tank is
almost impossible to reach so you will have to locate the wire somewhere in the
harness to ground it. Possibly on the back of the cluster itself.(That's why you need
the EVTM). The senders do fail quite often.

3. Odometer. If the Speedometer still works and the Odo doesn't, the speedometer head
is faulty. If neither part works, it could be the speedo head but is more likely the
Vehicle Speed Sensor in the transmission.

 Couple of notes: If you need to replace the fuel tank sender, pull the bed off to
replace it. It's much easier to do than dropping the tank. 30 minutes, 4 screws, 1
electrical connector, 8 bolts, 2 guys, and 6 beers. While it's off is a great time to
do the rear shocks. It doesn't get any easier.
 If you live in the rust belt, look at the leaf spring mounts on the frame and the
front to rear brake line where it connects to the axle hose while you have the bed
off. I just add this because these areas are VERY prone to rust. I've done the mounts
and brake line on 4 of these trucks in the past 6 months. If you live some place warm
with no winter salt, well then.................can I come live with you ;)