Transfer case broke
 

I have a 2001 7.3 6 speed electric shift transfer case and my truck only moves in 4wd now when I try 2wd it will not spin the back drive shaft but it will engage in 4wd and the truck will. Move fine all the gears in the tranny work like they should no resistance or tight feeling on anything was wondering what would break in transfer case and who makes a heavier replace ment