85 k5 rear end clunk 10 bolt

[SuperMidget]

my dad's 85 blazer has recently developed a noticeable clunk in the rear end, i watched today as we went from drive to reverse a few times...

the drive shaft spins about 1/8th of a turn then clunks to a stop while holding the brakes like there is a massive amount of slack in the rear end

any ideas for a simple fix or are the guts in the 10 bolt to far gone?

 

[82Scottsdale]

check the u joint going from the driveshaft to the yoke on the axle.

 

[GNEEnterprises]

If it is not a u-joint, then it could be the carrier bearings. If they wear out it will allow the carrier to move away from the pinion, which would explain the slop. The rear end will probably be making some noise as well. 10-bolt axles are very weak so start shopping for a 14 bolt!