Thanks for the suggestions.
I've checked the intake (as much as I can see) and didn't see the leak. The problem is visibility. Actually, I don't think that the 4.0 has any coolant going through that plastic intake manifold, anyway....

Unfortunately, the pressure tester won't help. I already know I have a leak. The problem is being able to see where it's coming from. If I could open a door in the firewall and peer thru from inside...

Pawpaw, I'm not smelling coolant in the cab. Having had bad heater cores in the past, I'm familiar with that smell. It would fog the windshield, too. But the heater is on the right and my leak seems to be on the left. I'll have to add the engine size to my sig (but it does say FX4).

Does anyone know if the 4.0 engine has freeze plugs? I couldn't find any reference to them in the shop manual. If not freeze plugs, do these engines leak from the head gasket? I jacked up the truck this morning and tried looking in from the drivers side wheel well. I could see that the split line between the head & block looked wet ( ), but I can't rule out the possibility that it came from above. Although I don't know of any coolant lines above this area.