Need some advice!!

[chevygoon]

Hello,
Here is my problem, my brother bought a 2004 HD 2500 with only 22500 miles on it and I am telling you it looks like showroom condition. He was coming to see me the other day and something went bad in the front differential and actually pulled hime towards the ditch. He said after he stopped and put it in two wheel drive it was ok but makes a grinding noise upfront. The dealer he bought it at said it is out of warranty and would not be covered because it is to old. My question is how many years are these diffs the same in the front? It has 4:10 gears with the floor mounted shifter. I feel horse**** because he has always been a Ford guy and wouldn't you know when he converts this happens. Also any idea what the front diff is new from GM? It just happened yesterday so I haven't had a lot of time to look at it. Let me know what you think.