Have a 2wd 04 tahoe that is racking up the miles - but still going pretty good.
We recently started noticing that when we turn to the right (make a full turn - not half way turning) that the whole vehicle will jerk about twice (popping noise when it happens). Any ideas oh which direction i need to look in order to fix it? It won't do it to the left...

 

Differential sounds like it's locked up...

 

I thought it had something to do with the differential as well --- took it to a transmission place and they inspected it, put in new oil and said it looked good. the only thing they noticed was that the rear u-joint was dry as a bone and he greased it up.