Mysterious grinding sound
 

I have a 95 F350 7.3L diesel 4x4 5spd. When coming off the line the truck makes a grinding sound from the front end. I only here the sound when i engage 1st and 2nd. Otherwise I don't hear it. Also I noticed my passenger side front wheel hub leaked a large amount of grease onto my rim. I'm trying to determine if the two are related or whether I am looking at 2 separate conditions. Thanks in advance for any help.