i thought i gave a decent explanation in your other post but i will try again.
first climb under the driver side of the truck and follow the linkage from the tranny to the frame.
from there you will see a second piece of linkage that is held to the first one with a pinch bolt. loosen that bolt (13mm if i remember).
then flip the piece of linkage on the tranny all the way to the rear, this is park.
get in the truck and put the shift lever into park.
crawl back under the truck and tighten that pinch bolt back up.
now get back in the truck and with the ignition in the "on" position and the engine off, click through the gears checking to see that you have full range of motion (park through 1st).
I also have a irritating noise coming from the trans area. I don't know anything about transmissions but it sounds like something, maybe bearings that are not lubricated, almost like metal on metal. It really sounds like AM static because it intensifies and detensifies with the rpms of the engine. I haven't had the truck very long and it was there when I got it. I had the valve body overhauled at the dealer so the trans has been serviced but the noise is still there.
I was hoping it was just outside noise coming through maybe a hole in the gear shifter area, or maybe the firewall. Other then the sound, everything is fine....as long as you keep the radio on so you don't pay attention to it.