This is for my 2003 duramax. So I just bought a used transfer case off a guy who said that it came off his 2005 2500HD with push button 4x4. It does look pretty close to mine, but on the transfer tag it says NP 246. Is this going to work in my truck, i need to get this thing in today but the last thing i want to due is pull it out to find out the 246 wont work. Any help would be greatly appriacated. Im doing a search as well, but wana start pulling this thing ASAP!
Thanks

No it will not work. The Allison is a 29 spline output shaft where the NP246 has a spline count of 27 or 32 depending on witch transmission it had. The NP246 usually came in half tons but will come in some 3/4 tons with gas engine.
The t-case you need is a NP263XHD. I can help you if you need one but you will have to pm me or i can pm you my number.

Dan