front differential emptying itself threw the overflow?

[H2duramax]

Hello all,
I just purchased a 2008 h2 around the first of the month and its burping up gear oil from the front diff. This has been off and on now for about 10 days. Everyone I have talked to told me it was probably overfilled and it would stop when it was at the right level. So today I pulled the fill plug and it was about 80% empty, why would this be getting hot and overflowing? It has not been in four wheel drive since i bought it. I put about two quarts in it and fully expect two see that come out over the next few days. Any ideas?

Oh last thing its a duramax conversion with allison and a hd transfer case.

Thanks for your time,
John