Range rover problem

I have a 1998 range rover 4.6HSE and I have a problem when I take off fast from start I hear a claking nios under neath the truck and I think that It is the trans fer case that is going bad is this thing hard to rebuild or is it a chain that has to be tightened inside or do I have a really bad problem on my hands.

Also when I am on the freeway on my passenger side of the car I under the hood I hear a loud noise like something is flapping under the hood or raddelling only when I go like 90mph or above. Does anybody know what is going on with these problems.