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Np 208 to 205?

Discussion in 'The Garage' started by Openheader2002, Feb 21, 2006.

  1. Openheader2002

    Openheader2002 Registered Member

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    I am new to the 4x4 world, I usually stick to cars. All this transfer case swap talk is giving me a headache. I have a 1989 suburban with a np208 case and I would like to swap a 205 in with a twin stick kit. Anyone know what has to be done to the driveshafts? I fully expect to have custom ones made up, but measurments would be nice. The truck is lifted 4 inches. And are any modifcations nessecary to bolt the 205 to a turbo400? Any advice would be greatly appreciated.
     
  2. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    Wasn't 89 the year they started using 241s? Sure you have a 208? Either way...

    You pretty much have to get the t-case bolted in and measure both at full compression and full droop... or at least as close as you can get. Measurements from other people's trucks is never going to be quite right. Believe me, I used measurements from other people... and it isn't worth the time saving. Do it once and do it right, its always the cheapest way in the long run. This truck isn't your DD... is it?

    Good question... the 400 may have a different length output shaft when mated to a 208 than a 205. I'm not a guru on late np205s/adapters... but pulling your t-case off and taking a measurement of how far out the trannys shaft extends beyond the housing will help a lot. I'm sure someone knows the answer off the top of their head tho...

    j
     
  3. Openheader2002

    Openheader2002 Registered Member

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    thanks

    Yeah the truck definitely has a 208. It is my daily driver too. I happen to beat the crap out of it on the trails though. Are their any real upgrades to do to the 208? HD chain or something.? The gear to gear in the 205 just seems to be the best way to go in my opinion though.
     
  4. hack500

    hack500 1/2 ton status

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    honestly a 208 is fine and they do hold up even behind a big-block. but if the internal pump craps out it may go ka-boom. and don't whack the case on anything - ya know, like, fallen trees, rocks, or small cars.

    if'n you are deadset on a 205 then you'll, most likey need a longer output shaft in the tranny and the correct th400->205 adapter.
     
  5. MEK5

    MEK5 1/2 ton status

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    The easier way to do the 208/205 swap is to find a late model round pattern 205 with adapter.This has the long type input gear which will work with your TH400 and the shaft stick,plus the adapter will be the short foot so your current cross member can be used.There will be shifter issues to address also but you want to go twinstick anyways so you all ready know that!

    Your front driveshaft will have to be shortened or replaced with the correct lenght one.You will need a longer rear shaft unless the 205 has a slip in rear yoke but probably still end up short not sure on that.

    If you come up with an earlier fiq 8 TH400/205 with adapter you can swap in the long type input gear and it will work behind your TH400 but you will have to change to the flat cross member.

    Other than all that there nothing to it:rolleyes:

    IMG00008.jpg
     
  6. Openheader2002

    Openheader2002 Registered Member

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    208 upgrades?

    Ok lol, well I don't want to hold my truck up for a week have driveshafts made. So does anyone know of np 208 upgrades? Fortunately I happen to have an extra 208 case lying around from a previous truck lol.
     
  7. Openheader2002

    Openheader2002 Registered Member

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    and not to sound like an idiot, but the extra np 208 case i had was bolted up to a turbo 350, will this be a problem bolting it up to the current turbo 400 in my truck now?
     
  8. MEK5

    MEK5 1/2 ton status

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    That extra 208 wont work because it only has 27splines and you need 32
     
  9. jekbrown

    jekbrown I am CK5 Premium Member GMOTM Winner Author

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    208 would be an ok case if it didn't have a slip yoke. Thought about maybe just adding a SYE to the case you have... or maybe swapping a 241 in with a SYE on it? Not sure what the deal is with the 241 goes as far as input spline count etc...

    j
     
  10. Openheader2002

    Openheader2002 Registered Member

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    I thought that the outputs on the tranny would be different as they are in rear wheel drive apps, but I was hoping that maybe gm would be cheesy and put the same in all the trans so the cases would just bolt up. Meh, I dunno, I might just rebuild the 208 that's in the truck.
     

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