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Swapping for 3/4 tons?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by nau81blazer, Nov 7, 2006.

  1. nau81blazer

    nau81blazer 1/2 ton status

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    Hey all,

    I know many of you have done this so I was wonder if you could help me. I might be getting ahold of some 3/4 running gear and was wonder what modifications would need to be made. I believe that they are out of a 74' k20. I'm going to be putting them into an 81' k5. Will the spring plates need to be moved? Will my steering bolt up to the new axle? Any modifications need to be made to brakes? Thanks for any input you can throw my way! :bow: :bow: :bow:

    --Adam
     
  2. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    The front axle is plug and play with the exception of the calipers, those will have a 7/16" banjo bolt instead of your 10mm banjo bolt so my suggestion is to unbolt your calipers and swing them out of the way and once the donor axle is swapped in bolt your calipers to it. The rear axle will be plug and play as well with the exception of the e-brake cables will be different but depending on the style of cables it has you might be able to use your existing ones over. The spring perches and shock mounts will all be correct but you will need the top plates and also a conversion u-joint.
     
  3. BKinzey

    BKinzey 1/2 ton status

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    Yeah, and you'll need........um:confused: Nope! I guess that's about it:D
     
  4. 73K5Kid

    73K5Kid 1/2 ton status

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    I thought also new ubolts for the 14 bolt :D . I am getting ready to do the swap soon as well. :eek1:
     
  5. 4X4HIGH

    4X4HIGH 1 ton status Premium Member GMOTM Winner

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    I would have hoped that would be a given but i was thinking i should have put that in there also. It would be someones luck to think they had everything needed for a weekend swap and once everything was out and the new stuff ready to install and all the 4x4 shops closed then they would find out they need new u-bolts as well.
     
  6. MattK

    MattK 1/2 ton status

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    new ubolts all the way around is a pretty good idea. be sure to buy plenty of gear oil, brake fluid.

    be sure you inspect the brakes.
     
  7. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Don't forget the new wheels . The 3/4 ton axles seem to have extra studs for some strange reason :wink1:
     
  8. nau81blazer

    nau81blazer 1/2 ton status

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    awesome!! Thanks for all the info guys!! The axles are in an existing vehicle so I'll make sure to get the u-bolts from him. The coversion joint can be purchased at NAPA right? thanks,

    -Adam
     
  9. BKinzey

    BKinzey 1/2 ton status

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    Or from a Vendor Right Here on CK5!:D
     
  10. BigEasy

    BigEasy 1/2 ton status

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    Anybody have that NAPA part # handy for the conversion U-joint? Also, I though I read somewhere that the rear driveshaft has to be shortened due to the 14 bolt diff being larger (pushing the yoke farther forward than a 10 bolt's)? As soon as I get my 14 bolt back from the rebuild/Detroit install, I'll be tackling this same project.
     
  11. XHitman396

    XHitman396 1/2 ton status

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    i lost the part number, and im sure someone else on here will give it up, but in case not, just got o NAPA and look at 2 u-joints from the 14bff and the 10b and measure the endcaps, then they'll have a little book they match them up with to find the right part #. well i know the driveshaft will not have to be replaced if you have an np208 (slip-yoke) t-case. otherwise im not too sure.
     
  12. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    Just for reference , there are TWO np208 slip yoke driveshafts . One in 1310 with internal clips for the 81-82 trucks with 12 bolts , and one in s44/3r for some 82 and all 83 up trucks with 10 bolts .

    Either will fit the np208 , but each requires a different conversion joint to the 14bff 1350 .

    This threads starter just bought a 10 bolt shaft from me for a np208 and informed me he had internal clips on a 12 bolt , I said what year , he said 81 with stock 12 bolt . So he needs a conversion joint for even his 12 bolt .
     
  13. imiceman44

    imiceman44 1 ton status

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    10 bolts have 1330 U joints
    12 bolts have 1310 U joints :D
     
  14. pauly383

    pauly383 Daddy383 Staff Member Moderator

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    10 bolts have s44/3r . Search button proves this , even though a well regarded member or two bought a truck with an aftermarket 1330 30 spline yoke :thumb:
     
  15. Slapperbar

    Slapperbar Retired Navy NDT Examiner Premium Member

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    Do NOT re-use the old u-bolts. Get new, much safer.
     
  16. nau81blazer

    nau81blazer 1/2 ton status

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    Thanks again for the hooking me up with that combo. I'm about to head to NAPA right now. Thanks again,

    --Adam
     
  17. filo

    filo Registered Member

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    for the 10-bolt it is Napa part # 240-0358. (1330-1350) I apparently have the s44/3r and not the 1330.
    According to Four Wheeler Jun '04...1330 has 1 1/16" bearing cap diameter and the 1350 has 1 3/16" bearing cap diameter. It turns out the s44/3r has 1 1/8" diameter. Back to Napa I go.:doah:
     

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