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what would it take .......

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by Terminaltsi, Jul 2, 2003.

  1. Terminaltsi

    Terminaltsi Registered Member

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    to put a np 205 in place of a 203 on a 73 blazer? my 203 is giving up slowly, and i don't want to try to find and install a beast like that, i'd rather have a 205 anyway.
    what mods are necessary?
     
  2. 70~K5

    70~K5 1/2 ton status

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    A 205 will bolt right in, all the holes are there allready. Driveshafts will have to be changed. The front one is shorter and the rear shaft is longer.
     
  3. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    So any old 205 will bolt in magically? I'm glad it's so simple a swap that there aren't any other details worth mentioning.../forums/images/graemlins/rolleyes.gif

    The donor 205 has to have the same input gear spline count as the 203 coming out. So if you have a TH350 now you'll need to find either a 205 that was once behind a TH350 and has the same 27 spline input or swap a 27 spline input into the donor 205. It has to be a passenger drop married style 205 too.

    I'd make sure you got the correct T-case adaptor as well. I think the crossmember will work but I'm not sure...

    Also there are different front output styles depending on the year of the 205 you find. Some have the yoke style front output and some have a flange style. I can never recall which is which but one is a saginaw style and the other is a Spicer style. Your front shaft may not be able to be simply shortened if the front output doesn't match what your 203 has. If the styles are different you'll need another double cardan of the correct style as well as having the shaft shortened.

    The shifter hole is no big deal and it should line up...but the shifter boot and stuff is different. You may be able to use the 203 plate and boot though.

    The devil is in the details...which never becomes more apparent than when you are swapping stuff.

    Rene
     
  4. 70~K5

    70~K5 1/2 ton status

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    Your right Rene, I gave the short answer and the devil is in the details. The easy way would be to park a donor truck next to his and swap every thing over that needs to be changed. But a 203 to 205 swap is easy on a '73. Another thing is the yokes on a 3/4 ton or 1 ton 205 are a different size than a 1/2 tons yokes. This would be a good time to go to 1350 or 1410 joints if you're having new driveshafts built during the swap. /forums/images/graemlins/thumb.gif
     
  5. Terminaltsi

    Terminaltsi Registered Member

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    ok, i knew there had to be something with the driveshafts and yokes and whatnot. thanks for the info. have any idea where i can get a 205 TC? local junkyards here suck. (not in phoenix anymore, now in louisville, KY)
     
  6. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    They're common enough...check out the for sale forum here.

    rene
     
  7. R72K5

    R72K5 Banned

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    also theres some 70's 3/4 tons with 203 that had one size joints on one end of the rear shaft and then another size on other end of the shaft, like in the 77 3/4 ton 4x4 203 trucks for example..
     
  8. Silver84k5

    Silver84k5 1/2 ton status

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    Spicer is the yoke, Saginaw is the flange /forums/images/graemlins/thumb.gif
     

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