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th350 to 700r4

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Roostr84, Aug 22, 2000.

  1. Roostr84

    Roostr84 1/2 ton status

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    I want to convert my th350 in my 69 blazer to a 700r4 overdrive. Has anybody done this and if so can you offer an advice.
     
  2. All you should need is to change the outputshaft in the transmision of the 700r4.This is a special adapter shaft.
    They can be aquired from Off Road Designe or from Advance
    Adapters.The tail housing on a 350 and 700 are the same all
    you need is the out put shaft I desribed above.
    Hope this helps.


    IF IT AINT BIG IT AINT BAD!!!!!!
     
  3. LittlePig

    LittlePig 1/2 ton status

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    Keep in mind the 700 is a bit longer than the 350. Also, get the biggest cooler you can, and make sure you get a later model tranny. the pre-86 ones are especially weak. After that, they were better, and can be built to handle a fairly high-output engine.

    Email: xiaozhu@my-deja.com
    ICQ: 84108805
     
  4. derek2002

    derek2002 1/2 ton status

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    Little Pig-
    Like you just said, I have also heard that the 700R4 is longer than the TH350/400s. Now, can the same driveshafts be used for both trannys? And also, the 350 and 400 are the same length, correct. Thanks!

    Later,

    -Derek
    1977 3/4 Ton & Blazer Project (Body Needed)
    http://www.4chevy.com
     
  5. sosamantx

    sosamantx 1/2 ton status

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    I have been told that the 700r4 is like 3 inches longer than a 350 turbo. I want to do a conversion on my Nova and they said that I will have to cut the driveshaft and rebalance it. I would rather just have one made by Denny's.

    Steve Sosa a.k.a. "sosaman"
    http://sosaman.home.texas.net/carpics.html
     
  6. BUDDY

    BUDDY 1/2 ton status

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    You will have to either have new driveshafts made, the lengths changed, (front shorter, rear longer), or move your engine foward about 1 7/8". That's the length difference. When I do mine I'll move the engine forward. No driveshaft changes and I'll get a little room between my firewall and distributor.

    HTH

    Buddy

    I've got my dream truck and it's a 72 K-5 that is getting there!!
     
  7. Roostr84

    Roostr84 1/2 ton status

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    Ok one more thing i was checking out advance adapters and they are saying that since i have a 69 blazer the only transfer case i have is the dana 20 piece and they don't make an adapter for this. they said this came in either auto or manual up till 71 when auto got the NP205. i have an automatic in mine.. so either i have to change to the later unit which if anyone can tell me how difficult this would be would help. or if anyone knows of 69's stock with the 205. Mine is an automatic by the way. Also how can you tell the NP205 from the dana unit. Thanks for all the help guys.
     
  8. bablazer73

    bablazer73 1/2 ton status

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    the 4wheel drive trans are the same overall length. I have a th350 and a 700r4 sitting on the floor next to each other. with the adapter for t-case on they are the same length. I also have the rear driveshafts from both trucks. they are also the same length. the 2 wheel drive versions of the 700r4 are longer than the th350's.

    your right. I don't understand the jeep thing!
     
  9. Roostr84

    Roostr84 1/2 ton status

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    Wow Bablazer,
    You are the first person to say that. Everyone else i have spoken to has said that the trans are different and people who have done the swap have said they either moved there trans or had one shaft cut and the other lengthened. I wonder what problems they ran into the they had to do that. I would think if they were the same that it would be a bolt in affair.
     
  10. bablazer73

    bablazer73 1/2 ton status

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    maybe the difference is the t-case used. both these trans had 208 cases on them. the 700r4 came out of my 84(lost 3rd and 4th gear) I replaced it with the th350 and used my 208 t-case over. perfect fit!! I have spare drive shafts for both style trucks and they all measure up the same. the t-case used in the swaps must be what changes the driveshaft lengths. I wouldn't use a 208 if I didn't have too!!

    your right. I don't understand the jeep thing!
     
  11. Roostr84

    Roostr84 1/2 ton status

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    If you replaced your 700 with a th350 and adapter then the adapter made up the difference. I am replacing my th350 with a 700 so the 700 will have an adapter which to me makes sense that it would be longer than the th350 without one.
     
  12. Wheels

    Wheels 1/2 ton status

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    You need the short tailshaft (Advance Adapters PN 50-6900) for installing a 700R4 in place of a TH350. This replaces the exsisting tailshaft in the 700R4 and tranny disassembly is required.
     
  13. River

    River 1/2 ton status

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    On the web site off TCi transmissions (www.tciauto.com go to transm en acces then on the bottom page is a buton transmission dimensions) is a page about dimensions.

    Greetimgs from Amsterdam,

    River `90 K5, 350, TH700R4, NP241, "33, 3.08, 10 bolt F, 10 Bolt R
     

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