4-wheel drive problem

The problem started with the four wheel drive not disengaging. As I was driving down the road it was making a very loud grinding noise. This noise would stop when I put it back into four wheel drive but then would resume when I put the shifter into two wheel drive or would go around a sharp turn. I jacked truck up so all four wheels were off the ground, when in four wheel drive all wheels will turn and no noise but when I put shifter back in two wheel drive the front wheels would stop turning but the front drive shaft would continue to turn and the grinding noise would start again. The noise appears to be coming from the transfer case but the front differential is leaking fluid out by the wheels. Both hubs have been replaced within the last month. Five speed transmission shifts fine. Any help would be greatly appreciated