Duramax Diesels Forum Truck of the Week
  #1  
Old 11-07-2019, 06:48 PM
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Default Which T-case to use?

For the 1/2 ton:


Can I use another Tcase in place of the 261XHD? These are as rare as hens teeth for sale, and people want a fortune for them.

I see quite a few 261HD from behind a 6.0/4L80E in the want ads and wondered if they'd work behind an Allison.

If so, would it simply bolt on and mate to the Alli output shaft, or do I have to change the Tcase input/output shafts/sockets?



Funny how 5 years later Im regretting selling the 261XHD I had from the donor. I can always stay 2wd.
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Last edited by TheBac; 11-07-2019 at 07:11 PM.
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Old 11-07-2019, 07:19 PM
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The 261HD has different input and output spline counts than the 261XHD
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Old 11-07-2019, 07:25 PM
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The input will be your biggest hurdle. I'm not sure how you would get the correct input to mate up to an Allison because there isn't one available that I'm aware of that is a direct replacement, but I'm sure it is possible to do it.
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Old 11-07-2019, 07:32 PM
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Question: then how have the guys gotten the 246 case to work with an Allison? New input socket in the tcase?
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Tom
"BBT" -- 2003 GMC CC/SB 4x4 12.14@111.15
"The Cruzer" -- 2014 Chevy Cruze Diesel -- the DD
"Kleshay" -- 2000 C5 Corvette -- the toy

Marlene (Molly) Bacon -- 1936 - 2019 -- RIP Mom You're already missed, at home and on the piano.

Two wrongs dont make a right, but three rights do make a left.
Reality is a matter of perspective.
This forum isn't for the weak of heart.....or wallet.
"Lets build a race car they said. Itll be fun they said. I don't know who "they" are.........but they need a good punch in the face!" -- mufflerguy (yb)

Last edited by TheBac; 11-07-2019 at 07:52 PM.
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Old 11-07-2019, 07:47 PM
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Tom

What kind of truck or SUV Do you need a transfer case out of?
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  #6  
Old 11-07-2019, 07:53 PM
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Dmax truck with manual Tcase. NP261XHD


I dont necessarily need it, Joe. I can always stay 2wd. Was just exploring options now that I have a 4wd chassis. Back in the day, Chris used the Dmax tcase with the 1/2 ton axles. I was just wondering if something else could be used.
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Tom
"BBT" -- 2003 GMC CC/SB 4x4 12.14@111.15
"The Cruzer" -- 2014 Chevy Cruze Diesel -- the DD
"Kleshay" -- 2000 C5 Corvette -- the toy

Marlene (Molly) Bacon -- 1936 - 2019 -- RIP Mom You're already missed, at home and on the piano.

Two wrongs dont make a right, but three rights do make a left.
Reality is a matter of perspective.
This forum isn't for the weak of heart.....or wallet.
"Lets build a race car they said. Itll be fun they said. I don't know who "they" are.........but they need a good punch in the face!" -- mufflerguy (yb)
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Old 11-07-2019, 08:00 PM
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To add: I have found multiple NP263Xhd Tcases for sale for reasonable prices.....but Im not sure just how difficult it would be to wire them to work properly in a manual Tcase truck without the OEM harnesses, or if its possible to convert them to manual.
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Tom
"BBT" -- 2003 GMC CC/SB 4x4 12.14@111.15
"The Cruzer" -- 2014 Chevy Cruze Diesel -- the DD
"Kleshay" -- 2000 C5 Corvette -- the toy

Marlene (Molly) Bacon -- 1936 - 2019 -- RIP Mom You're already missed, at home and on the piano.

Two wrongs dont make a right, but three rights do make a left.
Reality is a matter of perspective.
This forum isn't for the weak of heart.....or wallet.
"Lets build a race car they said. Itll be fun they said. I don't know who "they" are.........but they need a good punch in the face!" -- mufflerguy (yb)

Last edited by TheBac; 11-07-2019 at 08:37 PM.
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Old 11-07-2019, 09:10 PM
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Quote:
Originally Posted by TheBac View Post
To add: I have found multiple NP263Xhd Tcases for sale for reasonable prices.....but Im not sure just how difficult it would be to wire them to work properly in a manual Tcase truck without the OEM harnesses, or if its possible to convert them to manual.
Following, I am interested to know as well, as Iím building a gutted 2.6 pull truck but only have 263xhd cases around
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Old 11-07-2019, 09:12 PM
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I donít see why you couldnít make a 263 a manual shift. Rig up a manual shift linkage to the shift shaft that the encoder motor goes too and just do it that way. Iirc the shifter shaft could be turned and felt like there were ďdetentsĒ on each spot. Itís been a while since I had a t-case open though and never really studied that part
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Old 11-07-2019, 09:13 PM
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Hell, even if there are no detents or shifter wants to move out of selection, just build a shifter gate for 2wd, 4wd, etc
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Mike L is my role model. I want to be like him when I grow up.
James

02 LB7, LLY, LBZ, LMM, LML, L5P 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
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Old 11-07-2019, 09:22 PM
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Quote:
Originally Posted by TheBac View Post
To add: I have found multiple NP263Xhd Tcases for sale for reasonable prices.....but Im not sure just how difficult it would be to wire them to work properly in a manual Tcase truck without the OEM harnesses, or if its possible to convert them to manual.
What if I knew of a 2003 truck thatís a parts truck

I saw a transfer case in the bed and all the wiring is still there. Truck has been sitting a while outside but Iím sure the wiring is salvageable.
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Old 11-07-2019, 11:48 PM
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Quote:
Originally Posted by TheBac View Post
Question: then how have the guys gotten the 246 case to work with an Allison? New input socket in the tcase?
Iím afraid I canít answer that question. All I know is nobody makes a 32 spline input for an xhd case, and an input from an hd case will not fit according to multiple sources I checked with. Perhaps you can ask in that thread how theyíre making it work.

For what itís worth, it would probably be easier to make some sort of linkage to manually shift a 263xhd than to put a 29 spline input in a 261hd.
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Old 11-08-2019, 03:28 AM
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There are detents on the shifting mechanism of a 263. When we used one on our puller, ypu could shift it into ranges using a crescent wrench if the encoder was removed

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Old 11-08-2019, 07:17 AM
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Joe, if you think about it, next time you're by there, check on that Tcase....ya never know.

Did some more digging. It might be possible to fab a lever to use on a 263 case, but then you run into "how do you trigger the front diff activator?"
Ferm knows quite a bit about these from the posts Ive read. Would be interesting to get his perspective on it.



Meh, it doesnt hurt anything to stay 2wd. Less weight, less complexity. Just have to resort to old-fashioned tried-and-true chassis setup theory. No big deal.
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Tom
"BBT" -- 2003 GMC CC/SB 4x4 12.14@111.15
"The Cruzer" -- 2014 Chevy Cruze Diesel -- the DD
"Kleshay" -- 2000 C5 Corvette -- the toy

Marlene (Molly) Bacon -- 1936 - 2019 -- RIP Mom You're already missed, at home and on the piano.

Two wrongs dont make a right, but three rights do make a left.
Reality is a matter of perspective.
This forum isn't for the weak of heart.....or wallet.
"Lets build a race car they said. Itll be fun they said. I don't know who "they" are.........but they need a good punch in the face!" -- mufflerguy (yb)
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Old 11-08-2019, 07:30 AM
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Quote:
Originally Posted by TheBac View Post
Joe, if you think about it, next time you're by there, check on that Tcase....ya never know.

Did some more digging. It might be possible to fab a lever to use on a 263 case, but then you run into "how do you trigger the front diff activator?"
Ferm knows quite a bit about these from the posts Ive read. Would be interesting to get his perspective on it.



Meh, it doesnt hurt anything to stay 2wd. Less weight, less complexity. Just have to resort to old-fashioned tried-and-true chassis setup theory. No big deal.


put a hummer front shaft axle shaft in (makes it a solid shaft, no shift fork or collar needed) or buy one of the upgraded ones from dhd or another place

As for shift linkage, just grab a floor shifter from any gm truck/suv in your body year range. You may not use the full linkage but the shifter will bolt in easier and carries the pivot and just may have to do some modding time the linkage side.
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Mike L is my role model. I want to be like him when I grow up.
James

02 LB7, LLY, LBZ, LMM, LML, L5P 2500HD CC/LB dmax/alli "The Limo"

BIG THANKS TO: Mike L, Steve, Trent, Guy, Dan, Ruben, Josh H, Scott, Brian and everyone else who has put a hand in to help me.

best time to date: 12.39

motor died/bent rods = 3/11/11
back from the dead 7:04pm 4/9/2012

Limo is back in the garage, now driving a built chevy tracker
Tailgate Crew Member #4
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