Horrible noise coming from underneath

I have a horrible grinding/scraping noise that pulsates coming from where seems to be my front end.

Any idea what it could be? Its bad. like, "scrape...scrape.. scrape..." Only hear it when I am at slow speeds, but that could be due to lack of road noise at low speed.

I have thought of changing out all the drive train fluids, tranny, transfer case and both differentials to see if it would help due to something being dry.

Any other suggestions as to what it might be?

thanks!!!!!

 

I would jack up the front end & spin the tires by hand to see if the noise happens .....could just be a brake pad issue.