My F150 5.0 was running great. I had to drop a boat in the water and it's a steep ramp so I put her into 4 wheel drive low, When I did this a message on the dash told me to drive forward to engage. I did that and she popped in pretty loudly. Coming out of the boat ramp I put her back into 2 wheel drive and again she popped pretty loudly. I continued to drive and I heard another popping noise and she was no longer in drive. It did not matter where I put the gear shift she would not go into gear Even when I put her in park she was not in park, then after monkeying around back-and-forth trying to figure out what was going on when I put her into park she made a grinding noise and I can only assume she was in park because I couldn't move her. The shift linkage appears to be intact and working correctly and the grinding noise when we put it in park sounds like it is coming from the transfer case. I wondering if it could be the Transfer case motor? I'm hoping someone can give me a little guidance.