Need some help with general direction here. Whenever the 4wd is engaged on my 03 Dakota CC, it will work and engage, but it gets a bad grinding and squealing noise from drivers side front wheel. It only gets more pronounced when going faster. Once 4wd is off, it goes away. Any ideas as to where I should look?

 

The entire front drivetrain moves whenever the truck moves. The only difference is that in 4wd power is applied to the front differential.

I'd start with the front propeller shaft. It's pretty much where you say you hear the noise and it's not uncommon for it to go bad and make a racket.