1st and 2nd design d44?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by hawaiik5, Jun 30, 2001.

  1. hawaiik5

    hawaiik5 Newbie

    Jun 30, 2001
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    hello everyone,
    i was wondering what the differences were in the old and new 3/4 ton d44's. any pro's and con's? can parts interchange between the two?
  2. TX Mudder

    TX Mudder 1/2 ton status

    Jul 10, 2000
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    I think you are asking about closed knuckle vs. open knuckle d44's. The closed knuckle d44s are weaker because of the smaller ujoint (267-x I think.) Open knuckle d44's use the 297-x ujoint.
    The ONLY pro I can see to the closed knuckle is maybe less mud can get in the knuckle. Most people, however, ditch them ASAP.
    Open knuckle is the way to go.
    -- Mike

    <font color=blue> At some point I'll be done building my truck and can actually go wheeling. Until then, I guess sex and alcohol will have to do. [​IMG]
  3. thatK30guy

    thatK30guy 1 ton status Premium Member

    Jan 12, 2001
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    No, the closed knuckles have nothing to do with the '1st' and '2nd' design GM axles. Both designs are open knuckles, but have different size spindles, bearings, tie rods, axle housing tubes, u-joints, and backing plates. I did an explaination for someone else on the site and it was kind of long. I would need to search for it. I think it was Espen or Esteban.

    BTW, I found my post. Here it is:
    Ok, everybody pay attention here:

    GM has two different types of axles: the "first design" and the "second design". For those who dont know the difference, the "first" goes from 73-76. The "second" goes from 77 to 91. Some differences are:

    1. Backing plates are ALL diffferent. Both 1/2 and 3/4 ton for both designs are NOT the same thing. 3/4 tons are larger diameter than the 1/2 tons. There are currently 6 different types of backing plates. The 1/2 ton has the 73-76, 77-80, and 81-91. 3/4 ton is the same years, but only bigger around.

    2. Bearing hub and rotors are different. There are 4 types. 73-76 use a smaller wheel bearing on both the 1/2 and 3/4 ton. The 1/2 ton bearing hub is an internal drive. 3/4 tons were available in both the internal and external drives. 77 and newer bearing hubs are the same size wheel bearing. 1/2 and 3/4 tons are all internal drives. The differences in the rotor diameter is the fact that the 3/4 tons are larger around than the 1/2 tons. This is why the backing plates are larger around than the 1/2 tons. If you use a 1/2 ton backing plate on a 3/4 ton rotor, the caliper will NOT even align up with the bolts. If the 1/2 ton rotor is used with the 3/4 ton backing plates, the caliper will NOT have enough pad contact with the rotor.

    3. Spindles. 73-76 are one type only. They are "first design" small bearings. 1/2 and 3/4 ton spindles are interchangable. 77-91 spindles are "second design" and all interchangable between 1/2 and 3/4 tons. You cannot use a first design spindle with a second design bearing hub & rotor. The hub will wobble in place. If the second design spindle is used with a first design bearing hub, the hub will not even go on at all.

    4. D44 and 10B axle shafts are not interchangable. The D44 shafts measure: right - 36.13"
    left - 18.31"
    10B shafts measure: right - 35.46"
    left - 19.15"

    5. Steering knuckles. D44's have the infamous "flat top" knuckles on the passenger side. These are good for the crossover steering for where the steering arm is mounted on top of the knuckle after machine work and drilling has been done. The 10B knuckles have NO flat surface whatsoever. Machine work would be excessive to make the crossover work and therefore would be easier and cheaper to locate the correct knuckle off a D44.

    All in all, when doing a swap like this, try to round up the parts off one truck to use on the other. Such parts to swap over would be: backing plates, spindles, bearing hub & rotors, and if desired for crossover steering, the knuckles.

    The knuckles do NOT need to be changed if you do not plan on the crossover steering.

    It all boils down to this: D44 and 10B parts ARE interchangable from the knuckles out. Anything else from the knuckles in is NOT interchangable.

    In Estebans case, he has an 86 blazer and found 73 three quarter ton parts. He would need to use the 73 backing plates, spindles, bearing hubs & rotors.

    ALL calipers on both D44 and 10B are compatible with either axle. Even the first and second design axles are compatible with BOTH 1/2 and 3/4 ton calipers. So, whatever swap you plan on doing, you can retain your stock calipers.
    When stepping up to the big D60, this is a whole different ball game. Nothing is interchangable from the D44 and 10B to the D60.

    Any questions or comments, please let me know.

    When In Doubt, Whip It Out!

    Edited by thatK30guy on 05/25/01 05:53 PM (server time).

    Good luck.

    <font color=red>I m so we Todd did.
    I m sofa king we Todd did.</font color=red>
  4. bigjbear

    bigjbear 1 ton status Staff Member Moderator

    Feb 18, 2000
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    Marietta GA
    So if I read this right I can put the new bearings and rotors along with the spindles from the 10B on my '80 on to the flat top knuckles from my '73 D44. Right? If I use the 10B all is well, but if I use the D44 I will need to swap shafts to get the 5-297X u-joint. Are all (73-91) stub shafts the same-legenth, spline count, diameter-with the exception of the yoke? Right now I am planing on using the 10B because it has the right gears, but if I can come up with the money I want to use the D44 with an Ox Locker.

    Jim '80 GMC
    Freedom First!
    <A target="_blank" HREF=http://www.bigjbear.coloradok5.com>http://www.bigjbear.coloradok5.com</A>

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