1995 f-350 powerstroke crew cab. I pulled away from a stop sign today and the tranny made a loud pop then would not pull anymore tried putting it in park and it made a grinding noise. So I shut it off got out and engaged hubs and put it in 4wd and it took off and got me home. Any ideals on what gave out in the tranny. Friend of mine says he thought it might just be in the transfer case or is it time for a complete rebuild. Thanks