Let me preface this with i am a mechanic, I just dont deal with rear ends a lot. I just bought a 96 blazer 4wd, I was hearing a "popping noise" when I would make a turn... So I decided to do a quick visual inspection and everything looks ok. So I put my foot on the top of the tire and started shaking the car by pushing the tire with my weight and bingo i hear the noise..
It almost sounds like the axle shaft is sliding in and out. Im not sure what it would be. Any ideas would be greatly appreciated! Thank you in advance.

 

It's normal for the axle shafts to have a small amount of end play. I don't know how much is normal off the top of my head, but it's a SMALL amount. Could be enough to hear a noise if you rock the vehicle from side to side, though.

Most popping noises when making turns come from the front axle CV joints. I would look closely at those. If the boots are torn, they're probably junk.

 

If your get popping from rear end when turning it's your spyder gears check glove box sticker to see if you have G80 (limited slip)