Loud ping and shudder when turning

[AMT1379]

Help! Just took my 79 C10 Suburban out. Heard a ping while turning (heard the noise before but couldn't pin down the source). Heard it while turning this morning (first drive in cold weather) and felt what I think it the rear shudder while turning. Limped it home slow and now I'm trying to diagnose the problem. Locked rear differential was the first thing that came to mind, but I don't know how to verify without doing more damage.

 

[MrMarty51]

Jack up rear axle, get both tires off the ground, turn one tire, does the other tire turn the same direction ? if so, You have a posi. differential.
If other tire turns opposite direction, run, it going to explode.

 

[89Suburban]

Jack the rear axle up, spin the wheels listening for noises or vibration. Pull the cover off and do a visual. Depends if you have a limited slip or open rear.

 

[AMT1379]

Yes, it is a posi. I'll try jacking it up and see what I can find.