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

[Javier Gras]

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.

Javier
'88 Suburban 4x4

 

[dyeager535]

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.