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Need a transfer case

4K views 4 replies 2 participants last post by  bbrown 
#1 ·
I have a 03 2500hd 8.1 with the Allison transmission....need a new transfer case but I'm wondering if the transfer case off a 4l80e will mount to the ally?
 
#2 ·
Not enough information...Check the round transfer case tag on the back of the case and post the model number you have. My 4L80E has the NP263 t-case. I think the ally mounts the same case with an adapter ring but I'm not sure. Or you can check your glove box and find the RPO code for the case (NP1). What happened to your case?
 
#3 ·
It's either the 263 XHD or the 263 HD if its electric shift. If it's the floor shift t-case then either 261 HD or XHD the Duramax had the XHD...don't know about the 8.1 but probably the same.

NEW INFO: OK, from what I can tell by research...the Allison units should have the 263 XHD. There is a difference in the internal drive chain size and the input shaft spline count, 29 vs 32. So, you can NOT use one off of a 4L80E. Hope this helps.
 
#5 ·
No, your transfer case model# will still need to be looked-up....
 
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