passenger side valve cover
99 Durango doesn't have a Heater Control Valve, It only has a thermostat
Inside the transmission, on the valve body.
Throttle body
it is located on the right (passenger side) valve cover on your engine
No.
in the dipstick hole.
The PCV valve on a 99 GMC Yukon is found in the left valve cover. It allows trapped gases inside the engine to be recirculated and reused.
No
no, not from the factory
With a scan tool,
in side the transmission
I would say that my 1998 S-10 does not have a PCV valve, at all, anywhere.