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700r4 swap into a Blazer anybody do it?

Discussion in 'The Garage' started by Desert Rat, Mar 17, 2004.

  1. Desert Rat

    Desert Rat Fetch the comfy chair

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    Right now I have a TH350/NP205/GV overdrive setup in my 76 Blazer. I want to swap in a 700r4, probably from Bowtie Overdrives, keeping the NP205 and selling the GV unit. Anybody do this swap? I've searched on this topic but haven't found any definitive stuff. What are the issues? I understand the 700r4 is about 6 inches longer. From what I know so far, the tranny bolts right in, the lines to the radiator are pretty similar, and BO has a kit that makes doing the TV cable easy. How about the TC being farther back? Fabricated levers? /forums/images/graemlins/dunno.gif New hole in the floor? /forums/images/graemlins/hack.gif I can order the BO tranny w/ the NP205 conversion shaft installed.
     
  2. unick

    unick 1/2 ton status

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    the only thing I know about this is that you might have problems with the 700r4 and 205 if you use an adapter. The driveshaft will hit the trans pan from what Ive heard.

    Nick
     
  3. Desert Rat

    Desert Rat Fetch the comfy chair

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    The BO unit will come with the correct tail shaft installed. Shouldn't that help?
     
  4. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Why do you want to swap to a th700R4 when you have a GV OD unit? Seems like a waste of money to me. /forums/images/graemlins/dunno.gif
     
  5. Desert Rat

    Desert Rat Fetch the comfy chair

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    The GV unit ends up extending the length of the tranny/TC by quite a bit. So, with a 6" lift, my driveshaft ends up at a pretty steep angle. Plus, the GV units don't work in 4 wheel drive. Plus, I don't need to split gears, I just want an overdrive for when I do my highway driving out to Nevada to go wheeling. The GV unit is a great all around unit for someone who is towing, or doing mild trail running on dirt roads. It really isn't for serious off roading in my opinion. Lots of guys like to run them in a Suburban that sees a lot of tow or family hauling, but not in a serious trail rig. If anyone with a GV unit feels otherwise, feel free to pipe in. I haven't heard from anyone running a GV unit who uses it to wheel a lot. I'd rather keep it and save my money if I could.
     
  6. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    Ok, I can shed some light here for you. First off, a 700R4 is only 1 7/8" longer than a TH350. The tranny will bolt up like you said. If you use the short shaft in the tranny so you can use you existing T-case adapter you will have interference problems with your front driveline hitting the tranny pan. If you just have a 700R4 built with the factory 4x4 output shaft and then use the spacer this eliminates this problem. You will need to relocate the tranny crossmember backwards some, you will need to address the TV cable and the TC lock-up, and have your drivelines reworked to fit properly. As far as the shifter for the T-case is concerned you will need to move it forward approximately 3 1/2" or so so that it comes through the floor in the correct spot. If you have any questions feel free to PM me. I think you are local to me also so if you need quidance I could help you.
     
  7. Desert Rat

    Desert Rat Fetch the comfy chair

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    Sent you a PM and an e-mail.
     
  8. Cmoe

    Cmoe 1/2 ton status

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    I've heard that some people move the engine forward to instead of moving the t-case back.... This way the stock drive lines still work and the hole for the t-case is the same place. also adds some room between the firewall and the distributer..... I haven't done it yet but that's the way I'm thinking about doing.....
     
  9. ntaj*ep

    ntaj*ep 1/2 ton status

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    Did the swap front driveline is close but OK. Have had no other issues other than one broken Advanced adapter shaft....
     
  10. mike reeh

    mike reeh 1/2 ton status

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    [ QUOTE ]
    As far as the shifter for the T-case is concerned you will need to move it forward approximately 3 1/2" or so so that it comes through the floor in the correct spot.

    [/ QUOTE ]

    if the t-case is moving rear-ward 1.75", why would the t-case shifter have to move forward 3.5" to come out of the same hole /forums/images/graemlins/confused.gif

    I modified my np205 shifter and just welded on a 1.75" peice of metal to move the handle itself forward...

    mike
     
  11. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The 700R4 is 1 7/8" longer than a TH350, and then if you use the spacer it is about another 1 1/2" so that makes the original position of the shifter mounted rearwards 3 3/8" so it needs to be relocated forward by that amount for it to come through the factory hole in the floor.
     

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