Sounds like Belt but from under cab??

There is a screeching noise that sounds exactly like a belt but is coming from underneath the cab. Put the truck in neutral, with or w/o gas and it goes away. Put it back in gear and give it gas it will come back. It has been very intermittent, shows up now once or twice a week.

I checked the tranny fluid, seemed bit high but was okay. Looked at the axle joints and seemed a bit dry.. Thinking this noise is them needing to be greased. Any one had experience with something like this??