Pinion Yoke Spline Count on rear 10 and 12 bolts, same or different?

Discussion in 'The Garage' started by Javier Gras, Apr 13, 2004.

  1. Javier Gras

    Javier Gras Registered Member

    Feb 19, 2000
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    Dallas, TX
    Hello forum,
    The pinion on the 10 bolt rear on my 88 Suburban 4x4 /forums/images/graemlins/burb.gif has a lot of play which means loud banging noises, aka about to destroy itself. /forums/images/graemlins/frown.gif Bad seal and not enough oil, led to overheating.
    Therefore I need to replace it, I'm guessing it's probably not worth it to try and fix it and it's best to replace it as a unit.
    I have a wrecked 79 jimmy 4x4 with the 12 bolt, that should "just bolt up" /forums/images/graemlins/thinking.gif, but I have doubts that the U-joint is the same.

    So my question (about time) is, if the u-joint is not the same, can I replace the pinion jokes from the 10 bolt into the 12 bolt, are the splines, length, etc the same?

    What other issues may I encounter?
    Shock mounts, spring pads, and brakes should be the same, I need to check the Jimmy's gear ratio (Sub's is 3.07).

    Thanks for your time/help.

    '88 Suburban 4x4
  2. dyeager535

    dyeager535 1 ton status Premium Member

    Dec 13, 2000
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    Roy WA
    I have (supposedly) a 12 bolt yoke on my 10 bolt rear. Since the stock 1974 K5 driveshaft bolted right to it with a "stock" u-joint for the '74, I have to say that it is indeed a 12 bolt yoke.

    Previously to use the old driveshaft with the '86 10 bolts, I had to use one of the adapter u-joints with different size caps.

    I have a feeling though, that there is some variation in this, since cars had 12 bolts too, and IIRC, this is where my yoke came from. (bought it from someone on here a long while back, so can't recall the exact details, nor can I PROVE what it is from) Perhaps pinion spline/size never changed for the yoke, but it may have too.

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