If you pull the needles off the instrument cluster how do you make sure the pointer gets back on in the correct position? I took the needle off an old cluster and I did not notice any way of getting it back in the same place.
What most guys will do is get the truck up to operating temp, then take a picture or make a pencil mark on the gauge faces to note the position of the needle.
If you haven't already done what superduty4x4 suggested what I did was remove the plastic cover, start the truck and waited till it was warm then set the needels, as far as fuel make sure the tanks full.