A 1998 Dodge Ram does not have EGR.
Yes
It doesn't have an EGR.
It doesn't have one.
You don't have a heater control valve for this truck.......
It is the small plastic elbow that is on the top of the valve cover.
The sensors on the valve body (inside the trans) are different. You will need to switch them.
Yes
There wasn't a 1998 Dodge Ram 1500 diesel.
Inside the trans. It is the part on the valve body with the long wiring pigtail attached.
It is part of the pressure transducer inside the transmission, on the valve body.
No.