in the heater box behind the dash on the passenger side of the truck you have to remove the dash to get to it
You don't have a heater control valve for this truck.......
gas tank
It is part of the pump module in the tank.
The core is probably plugged.
Yes
There wasn't a 1998 Dodge Ram 1500 diesel.
Heater cores in all vehicles are up under the dashboard inside the vehicle.
No.
No, the 1994 has a hydraulic governer. The 1998 has a electrical governer.
Yes, that would be a good idea given the age of the truck.
There are two. They are located on each side of the catalytic converter.
It is the small plastic elbow that is on the top of the valve cover.