My son has a Ford Ranger 4x4.When 4 wheel drive is engaged there is a grating noise coming from the two front wheels when cornering,it is ok on the straight.Anyone had a similar problem on any 4x4 vehicle.
should have added also turn these same free wheel hubs to unlock positions and see in which positions the noise goes out.
If your 4x4 has auto free wheel hubs confirm source of noise by jacking up each/both wheels and turning the wheel in the driving direction.
Mind you look at the condition of the brake discs and pads and also feel for play from the wheel bearings.
Unless your front diff is leaking oil these diffs are meant to last .