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Tharf is my hero :read:
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Fantastic write up. I finally located an NV4500 from a 94 with the lower granny gear. Pretty much same assembly you picked up and for nearly the same price. Going to get it this weekend and spend the rest of the winter gathering the rest of the parts. I do believe ill have one of, if not the First four door Tahoe to get this conversion.
 

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02GMCtruck
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Discussion Starter · #44 ·
Looking forward to seeing that conversion, should be pretty bitchin'
 

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Tharf is my hero :read:
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Its in my garage. Im going to have to do alot of homework on this swap though. I wish I could get in your head. What did you have to change with your 241 to make it adapt to the 4500? I think a parts list could be super beneficial to me. Im going to need every part you bought. What I came home with is almost exactly what you scored minus the pedals. I was lucky enough to find a 94 model with the lower granny and reverse gears. It was pulled from a 1 ton Dually with a 454. So many things to figure out though. Just realized I need a 400 Flywheel. Shame I have the 454 one with its mating clutch on my floor and its just a huge paperweight to me. How do you like your clutch choice? I was thinking Centerforce but dont have too much experience with either.
 

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02GMCtruck
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Discussion Starter · #46 ·
Its in my garage. Im going to have to do alot of homework on this swap though. I wish I could get in your head. What did you have to change with your 241 to make it adapt to the 4500? I think a parts list could be super beneficial to me. Im going to need every part you bought. What I came home with is almost exactly what you scored minus the pedals. I was lucky enough to find a 94 model with the lower granny and reverse gears. It was pulled from a 1 ton Dually with a 454. So many things to figure out though. Just realized I need a 400 Flywheel. Shame I have the 454 one with its mating clutch on my floor and its just a huge paperweight to me. How do you like your clutch choice? I was thinking Centerforce but dont have too much experience with either.
You will need a 32-spline NP241 to be mated behind your NV4500. The current NP241 in your truck would be 27 spline. Now you can go about this in two ways, simply get a 32spine t-case, or swap the 32-spine input shaft & bearing into your case. Literally the only difference between the two cases is the input shaft & bearing, other than that, nothing.

Yeah, I ran into the same issue with my truck and had to buy a new flywheel as well. You CAN re-use the clutch from the donor rig, I almost did, but since your in there it's a good time to put a new one in. I really like the Hays Supertruck clutch I put in my truck. It works well IMO, I can slip it if needed offroad, but it also holds well. I've heard they can take some abuse. It is pretty easy to drive with, as a friend with a manual mustang said it was easier than his car clutch :lol:

Hays and centerforce are made by the same company, however the centerforce clutches I've had experience with grab too hard.... there isn't any slippage in them IMO.
 

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Tharf is my hero :read:
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Excellent info. Thank you very much. If you have a chance to throw out some part numbers on the parts you bought I would greatly appreciate it.
 

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02GMCtruck
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Discussion Starter · #48 ·
Which part numbers do you need?
 

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Tharf is my hero :read:
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The GM parts I cant get through my local dealer. I guess just the Clutch Kit.

Im looking into the input shaft swap. I take it thats the route you went? If so where did you source your input shaft? Drivetrain.com lists two different ones: .630" wide input bearing or .940" wide input bearing.
 

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02GMCtruck
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Discussion Starter · #50 ·
I grabbed my flywheel and clutch from Jegs, and the oil direct from Amsoil. The only other thing that I couldn't get at the dealship was the small shift boot that fits on the top of the shift tower (mine was tore). You can still get them from quad4x4.com on their small parts page.

I got the transfercase with the transmission. The only reason I swapped input shafts is because my NP241 is the harder to find passenger drop (because of my SAS). The 32-spine pass drops are like gold, unlike the IFS driver's drop version. Pass drop NP241s were only used 4 years, and only 2 of the years were electric speedos.

I honestly think you'd spend about the same finding a used case in the junkyard, and just selling your old case. I know the input shafts run about $150 alone, while a used t-case runs under $150 all day long (i picked up my current NP241 for $50).
 

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Tharf is my hero :read:
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Ok. thanks again for the help. Lots of homework ahead. Ill probably start my own build thread soon as well
 

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02GMCtruck
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Discussion Starter · #52 ·
Not a problem. Let me know if you have any other questions!
 

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Tharf is my hero :read:
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Ok, heres one for ya,

Regarding the 32 spline input t-case, would that not also have a larger output shaft diameter as well. Seeing as its a 3/4 or 1 ton application. In the case of my Tahoe, I would have to get a custom driveshaft due to the specific length. Although considering I have a 14 bolt already back there. The weakest link in this whole thing would be the 1/2 ton driveshaft among every other piece of the drivetrain being of 3/4 ton or larger strength.
 

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02GMCtruck
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Discussion Starter · #54 ·
Slipyolk spline is the same, the 3/4ton ones would just have a larger u-joint IIRC. I never checked mine however.
 

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02GMCtruck
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Discussion Starter · #56 ·
The NV4500 did come in 2wd form. I have no idea if a nv3500 driveline will work or if they are the same length.
 

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Tharf is my hero :read:
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Were you able to use an 11" or 12" clutch?

Jegs lists the 11" (Part #90-155) for 271.99 and the 12" (Part #90-102) for 251.99.

I have to use a flywheel for a 400 crank and the Jegs Flywheel says its for an 11" clutch,
however any other 400 flywheels with 168 teeth say 11 or 12" clutch.
Would be a shame to spend more money on a smaller clutch right
 

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02GMCtruck
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Discussion Starter · #58 ·
I'm using a 12" clutch with a 14" flywheel.
 

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Tharf is my hero :read:
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Hate bothering you again but im at a snag with the clutch selection here. The Hays application page says I should be running the 90-103 but that is a diesel application in size 12-1/4". I think that might be too big and I was told the 12" clutches tend to chatter. Have you had those problems at all? The 90-155 looks to match but its only 11"

What Hays part number did you go with? Ive got everything else.
 
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