GIjoe

ok here is the story.... I was in 4hi last night and when I shifted into 5th gear, I heard a sound that was kinda frightening... it was a kinda "wa wa wa" sound (if that makes any sense) I THINK that it might be that some how the axles timing is off... again, if that even makes sense. I'm not the mechanic type..... soooo yea, what do you think it would be?

I dont hear any grinding or anything and 4x4 still works and functions.... thanks everyone!