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Help ..trans interchange

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by talison79, Oct 18, 2001.

  1. talison79

    talison79 1/2 ton status

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    I'm going to get a temporary transmission from the yard, so I can rebuild mine. What I need to know is what can I pull from that will interchange? I heard 69 -79. Does it have to be from a four wheel drive? Or can I use parts from mine? It's a 79, 350, th350, 203 all stock.
    Thanks Guys
    Talison79
     
  2. dyeager535

    dyeager535 1 ton status Premium Member

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    You COULD use a 2WD one, but you'd need the output shaft out of the one you want to rebuild, so thats not a viable option. Not sure if 4wd cases on these were known to be thicker than 2wd, but TH400's supposedly are this way. Get a 4wd one, although, if you can be without that vehicle, worst case scenario, it will only be down a few days if you really work at it. (so no need for spare)

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  3. SKI-'84K5

    SKI-'84K5 1/2 ton status

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    what gear ratios came stock for your setup, i am thinking about picking up a 79 and would like to know which set of axles i want to use 84 or 79, thanks
     
  4. talison79

    talison79 1/2 ton status

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    The reason I ask is because I'm not having much luck finding four wheel drive anything at the local junk yard, but for $40 bucks I can't complain to much. lots of 2 wheel drives. The gear ratio in mine is 3.40. Most of the ones I've seen are either 3.08, or 3.42. The twelve bolt is a little beefier than the 10 bolt from an 84. There is a post from a long time back where some one asked about breaking a twelve bolt and it is pretty rare. The front 10 bolt is a lot more likely to lose U joints. Might as well go with one ton stuff. I know its probably over kill, but its like a gun, it's better to have it and not need it, than need it and not have it. Plus its just damn cool.
    Talison79
     
  5. Executioner

    Executioner 1/2 ton status

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    Whats you definition of Interchange ?
    Best guess is a th350 that is/was married to a NP 203 from 1973 to 1979.
    1980, all had NP 205, with rear slip yoke, so that year is not going to interchange ?
    Good luck
     
  6. kchecca

    kchecca Registered Member

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    How hard is it to swap output shafts between TH350's? Specifically, I have a line on a newly rebuilt TH350 out of a car, so it has a 6" or something output. Could I *easily* swap the output shafts and put it into the Blazer?

    --------------------------
    Keith C
    Bigbird '00 Jeep TJ
    Grandpa's '77 Blazer
     
  7. dyeager535

    dyeager535 1 ton status Premium Member

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    you have to take the whole trans down, and pull it out the front of the case : )

    Thats why I said 4wd spare or just rebuild it and let the vehicle sit while you do.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  8. kchecca

    kchecca Registered Member

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    That sucks. There goes that plan. You would think they would make it easily removed from a rear cone or something.

    What about the engine itself? Would a '79 car 350 drop in place of my '77 K5 350 easily? This deal might be worth the $200 since the engine is only 35k old?

    --------------------------
    Keith C
    Bigbird '00 Jeep TJ
    Grandpa's '77 Blazer
     
  9. dyeager535

    dyeager535 1 ton status Premium Member

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    Better watch what you call "easy" : )

    Yes, it should be a bolt in. However, things like exhaust and what not could cause some small headaches that drag the project out. At least thats what happens in my case.

    (can you say:swap tailgate, estimate 30 minutes, find out wiring harness is different, no wiring tools on hand, end up taking entire tailgate apart (both of them) just to swap wiring and lock cylinder. Get it back together, and even after cleaning up the tailgate lock switch, the key open STILL doesn't work. Total time for 30 minute swap? 4 hours, and not even really done.

    Dorian
    My tech/links page: <a target="_blank" href=http://www.dorianyeager.com/index2.html>www.dorianyeager.com/index2.html</a>
    Why insist on counting when the ring gear has the tooth counts stamped in?
     
  10. talison79

    talison79 1/2 ton status

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    Hey thanks guys for the responses. I'm about to head out for another day of searching. Hey kchecca pick up a manual for the Gm transmission rebuild and take a look. If you can take something apart, and put it back together, and keep it clan you could do it. If it saves you quite a bit of money, it might be worth it. Its only 87 parts for the th 350 stacked on top of each other. Ok maybe not easy but look at it as a good practice.
    Talison79
     
  11. talison79

    talison79 1/2 ton status

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    It means to change by putting each of two things in the place of the other; to change in a reciprocal manner; as to interchange places. If you need help with any other words, just let me know. I'm always willing to help when I can.
    Thanks,
    Talison79
     
  12. FastEddy

    FastEddy 1/2 ton status

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    You can use the 2wd turbo 350 in your 4x4, you just have to chop off about an inch and a half off the output shaft, after you remove the tailstock...it must be a short tailstock ( 6 inch) turbo 350 out of an early(72 and under) 2wd pickup, or out of any mid sized chev car from mid 70's(malibu, monte, nova, etc) this is sort of a poor mans fix but we have done it here a couple years back, the problem is that you don't have as much of the splines engaged in the transfer case, as you would with the proper output shaft.....I would definitely trust it though for a temporary fix to tide you over, as long as your not running heavy horsepower and like to stand on it....hope this helps, you should be able to find a used short tail turbo 350 very cheap at the wreckers....just my 2 cents...ED
     
  13. talison79

    talison79 1/2 ton status

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    Man, Thanks ED,
    U dah man. Poor man fix good. That is great information, just what I was looking for. I just can't seem to find that extra money, that I had laying around the house.
    The yard that I go to they charge $60 for any transmission with warranty, if it don't work bring it back and get another one kind of deal. The problem is they don't have any four wheel drives right now.
    I am running a stock 350 mostly highway and it only has to last maybe a month or two till I can rebuild the old one. Do you recall how much less of the spline area is in the tranfer case?
    Thanks
    Talison79
     

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