Since yours is a 96 you should only have 1 sender. The 96-98 had the gauge ran by the pcm with no need for a second sender.
The one on the thermostat should be the only coolant temperature sender you have. The 93-95 4.0's had a second sender on the very back of the block, under the wiring for the injectors, 3" from the firewall and a ***** to change.
If a week goes by without needing to replace something, pinch me because I must be dreaming.