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Can I replace my 28-sp axles with 30s?

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

  1. txbartman

    txbartman 1/2 ton status

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    My truck has its stock 28-spline axle shafts in its original 10-bolts. Can I simply replace them with 30-splines when I replace my gears?

    Brian

    85 GMC Jimmy <a target="_blank" href=http://tx85gmcguy.alloffroad.com>tx85gmcguy.alloffroad.com</a>
     
  2. HarryH3

    HarryH3 1 ton status Author

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    Yes, as long as you have the correct side gears in the diff to match the 30 spline axle shafts.

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  3. kpanza

    kpanza 1/2 ton status

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    Just a note - I saw your other post about you putting in a Detroit in the rear - just make sure you remember to order a Detroit for the new 30 spline axleshafts, not your 28s! You probably knew that, just making sure! [​IMG]

    Also, if I was you, I would just save the money on the front and leave it open. Then, when you catch the wheeling bug (which WILL happen, it happens to everyone!), you will have saved money and will then be able to afford the ARB for the front!! [​IMG]
     
  4. txbartman

    txbartman 1/2 ton status

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    ARB is probably where I will eventually go. I have enough other things to spend my money on right now. I just thought if I could find a posi for not too much money would it even be worth installing?

    85 GMC Jimmy <a target="_blank" href=http://tx85gmcguy.alloffroad.com>tx85gmcguy.alloffroad.com</a>
     
  5. HarryH3

    HarryH3 1 ton status Author

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    There's a lot of labor involved in swapping out the front diff. You have to pull the wheels, brakes, spindles and axles from both sides before you can remove the diff. [​IMG] Not a job I'd want to do twice. [​IMG]

    <font color=black>HarryH3 - '75 K5</font color=black>
    <a target="_blank" href=http://www.angelfire.com/super/ThunderTruck>www.angelfire.com/super/ThunderTruck</a>
    It's a great day to be alive...
     
  6. 6.2Blazer

    6.2Blazer 1/2 ton status

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    Yes you can, but it does require replacement of the carrier (i.e. differential) with one with the 30 spline side gears in order to mate up with the 30 spline shafts.
    In a stock open differential, normally you could simply replace the side gears with the appropriate pieces. However, when it comes to the 10-bolt corporate 28 vs. 30 spline I believe that the carrier was actually machined out (at the holes in the side where the axles slide into it) to make clearance for the larger diameter 30 spline shafts......basically, while the 30-spline side gears will interchange with the 28 spline versions I don't believe the hole in the 28 spline carrier is big enough for the 30-spline axle to fit through.

    If you are replacing the stock carrier with something like a Detroit or a posi, it doesn't matter as long as you get a 30-spline Detroit or posi.
     

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