K10 Rear axle ID

[T-roy K10]

I know it’s a 12 bolt, even though everything I read says a 1985 k10 never came with a 12. Lady at DMV said it was either military or some government agency. It has the loud clunk in reverse and seems to have too much okay when turning yoke by hand (nothing up and down). Limited slip is also worn out and axles/wheels wobble slightly so they are bent.
the question.. I need to pull the axles to Id the splines and length or does anyone know those specs?

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[legopnuematic]

From the factory it would have been a 10 bolt, someone along the way swapped one in. They are basically a direct swap. My friend put his 87 10 bolt front and rear under his 75 K5, with the dana 44 and 12 bolt from the 75 under the 87 to make it still roll.

Why would someone swap a 10 for a 12? Who knows at this point.

AFAIK, all 12 bolt truck axles are 30 spline, 1970-1981 12 bolts should all use the same axle lengths. 5 or 6 lug depending on 2wd or 4wd.

With that said, safest bet is to pull them to inspect and verify to be certain.