Transfer case info

[Doonatic]

Hey yall, got a question for you. For the 2003 2500hd’s, Chevy offered 3 different types of transfer cases. Does anyone know how to identify which transfer case is installed in the vehicle one may have.

 

I am moving into my 3RD transfer case (factory installed chain ground a hole through the case years ago, dealer installed a “new” used one, and now this one will not engage reverse). I am vigorously searching for a new case NOW, because I am afraid my vehicle will leave me stranded very soon. (Side note: I get a grinding noise-like the chain is rubbing ONLY during coasting.)

 

So if anyone can help me find the part numbers or the direction to locate said replacement parts, that would be amazing.

[OldGuy96]

Are you sure it's the transfer case? If it will engage 4WD Hi and Lo, then the transfer case isn't your problem. If the truck won't go into reverse, you probably have a transmission problem.

[PTXer]

What is your RPO code?  That should narrow it down.  It might be stamped/labeled on the case as well.

[Doonatic]

21 hours ago, OldGuy96 said:

Are you sure it's the transfer case? If it will engage 4WD Hi and Lo, then the transfer case isn't your problem. If the truck won't go into reverse, you probably have a transmission problem.

Old guy, i thought that as well, however when it is in reverse the noise that is emmitting from underneath is coming from the transfer case, not the transmission. Its as if it is a solenoid motor that is not engaging.

[Doonatic]

8 hours ago, PTXer said:

What is your RPO code?  That should narrow it down.  It might be stamped/labeled on the case as well.

RPO code?

[newdude]

GM used two transfer cases in 2500HD trucks (2001-2007 classic), the NVG 261 and NVG 263 transfer case.  The 261 is the manual shift 2 speed case (floor shift), RPO code on the build label is NP2.  The 263 case is the electronic shift 2 speed case, RPO code on the build label NP1. 

 

There is some internal differences in the cases between the gas mated to 4L80, and gas/diesel mated to Allison cases in terms of gears, chains, input shafts, etc.   

 

I believe ones bolted to the Allison had "HD" or "XHD" tagged at the end of the case number on the NVG stamp on the rear.  NVG261/3 XHD/NVG261/3 HD. 

Edited September 19, 2018 by newdude

[carkhz316]

3 hours ago, newdude said:

GM used two transfer cases in 2500HD trucks (2001-2007 classic), the NVG 261 and NVG 263 transfer case.  The 261 is the manual shift 2 speed case (floor shift), RPO code on the build label is NP2.  The 263 case is the electronic shift 2 speed case, RPO code on the build label NP1. 

 

There is some internal differences in the cases between the gas mated to 4L80, and gas/diesel mated to Allison cases in terms of gears, chains, input shafts, etc.   

 

I believe ones bolted to the Allison had "HD" or "XHD" tagged at the end of the case number on the NVG stamp on the rear.  NVG261/3 XHD/NVG261/3 HD. 

Just tagging on to this to confirm what you mentioned about the Allison-equipped trucks (8.1/ Duramax). They are 261/3 XHD as you stated. Only real differences with the XHD variants are the larger output shafts, and different oil pumps. Otherwise, most of the guts are the same.

[PTXer]

You can get those RPO codes from the label on the inside of the glove box. 

[newdude]

10 hours ago, carkhz316 said:

Just tagging on to this to confirm what you mentioned about the Allison-equipped trucks (8.1/ Duramax). They are 261/3 XHD as you stated. Only real differences with the XHD variants are the larger output shafts, and different oil pumps. Otherwise, most of the guts are the same.

 

Thanks for the clarification. 

[LarsonFarms]

Will a 2005 transfer case work in a 2008 Chevy 1500?

[swathdiver]

On 5/23/2022 at 8:32 AM, LarsonFarms said:

Will a 2005 transfer case work in a 2008 Chevy 1500?

It is not a direct bolt on, plug in and go.  I would say no, but exactly which transfer cases are in question here?  My brain thinks of the 246 and MP3023 which are electronic.

[Steven suzor]

Mine is stuck in 4 low will not come out. Sounded like an explosion constant grinding even when truck is in park.  My truck is still in neutral and making the grinding noise. 2003 GMC Sierra 1500

[davester]

No, get the same TC as what's in the truck.

 

You might be able to manually shift what mode the TC is in, by removing the encoder from it, then manually rotating the post to the mode you want.  It may take some fiddling ton find which position is for 2hi