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TH 400 to TH 700 swap ?

Discussion in 'The Garage' started by fireinthehole, Mar 12, 2004.

    I am sure it has been covered before, but I get tired of sifting through the search feature. Anyway, is this swap a PIA? I am considering this as a better way to go instead of getting a Gear Vendors OD unit. It will go in my 89 Sub, with Th400,np241. The actual swap I dont think will be much hassle, except for shortening the driveshaft. Its the other stuff, wireing and cables and such. Just looking for info from people that have done it or researched it more.

    Thanks-Mat
     
  1. blasterD

    blasterD 1/2 ton status

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    Your transfer case will not bolt up to the 700r4. You should have a 32 spline 241 behind your TH400. You will need a 27 spline 241 or a 208 and the correct adapter to mate up to the 700r4. You may not need to mess with any driveshafts. I believe the 700r4 is about the same length as the th400 but I'm not absolutely sure.
     
  2. wayne

    wayne 3/4 ton status

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    You will need to change the input shaft on the t case. Your driveshafts should work fine. If you are serious I will swap your input shaft for the one you need. I will also swap you the correct t case mount. The swap is fairly easy otherwise.
     
  3. Thanks for the offer, I am just in the info gathering phase right now. I need a second vehicle first so I have transportation while my rig is down.
    What about the TV cable and all that with the 700? How do you get that working as well as the speedo? I have a mechanical one now, and I know that are electronic on the th700/241 combo.
     
  4. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    First off the t-case is where the speedo connection is at so if you keep your existing t-case than the speedo is a non issue. If you find a 27 spline 241 than just make sure it's an 89' and it will still have the mechanical speedo. Do you have lockup on that th400? That will have to be addressed if you don't because a th700 has a lock up converter.
     
  5. wayne

    wayne 3/4 ton status

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    There are companys that make brackets for the tv cable hook up. Your speedo will be fine if you use the same case. The electronic speedo only started in 90.
     
  6. Torque convertor in non-lockup. Good on the speedo cable, I forgot the switch in 90, thats also when rear ABS started.
     

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