Not Sure What To Replace

[BigTruckDriver]

Hi all...

So a while i back i started hearing this noise from time to time, sounded like i was dragging something in my undercarriage. When I got out and checked, nothing. I noticed that the sound only happy in the low gears; once i reached say 2nd or 3rd is was smooth sailing. The other thing that happened is, living in New England, I use my 4WD from time to time in the snow. I noticed that whenever I turned it off, a warning to Service 4WD came up for a brief spell.

 

When I got the vehicle looked at, they said my REAR differential fluid was low. This was odd, as I had just had it changed not 2 weeks prior to this happening. They topped it off and I asked them to check for a leak.

 

Fast forward a couple of weeks and now this grinding noise is back consistantly and is making my car jump from time to time off the life. It also makes a horrible noise when going in reverse. I went to another service dept. and they said that my FRONT differential fluid is mud and filled with shards of metal. So they changed it, but said that the damage maybe done and I could possibly need a new front end differential.

 

So after all that, my question is simple. What do I need to replace? The entire assembly, the housing? what? The differential has a lot of pieces to it and I don't want to spend $1200-1500 replacing something that does not need to be replaced.

 

If anyone thinks that it may be something else, I am also very much interested in that also. Thanks for all your help.