Water temp gauge

I have a 95 sport 4x4 and a couple years ago (in high school), my dad and I swapped a 97 grand cherokee 4.0l into my Cherokee, it had a 4.0l factory but had a lot of mile on it was then reason for the swap. Everything went very well everything hooked up except for the water temp gauge. Does anyone know how I can hook it up? The stock motor had a plug on the back of the head and it plugged straight up but the 97 head does not have that. Any help is greatly appreciated.

Use the later thermostat housing and screw your sensor into it.