Rattling noise

[jeremy5780]

I have a rattling sound when I have my hubs locked, but it only rattles when accelerating. Put the hubs back in free and it goes away. Any ideas what it could be? When I say rattling it sounds like a skid plate rattle or like an exhaust cover rattling on a exhaust pipe. Metal on metal rattle

 

[Torxhead]

First guess would be the front driveshaft, second would be front u-joints, wheel bearings and or Transfer Case .