I'm hearing a single pop or knock sound coming from the passenger side rear when I make a left turn. I dont see anything unusual underneath. Anyone know if this is a symptom of something? Does it in reverse too.

 

I suspect, that you have a bad axle U Joint. U Joint failure is a common reoccurrence with these trucks. I keep replacements for the drive line and front axle on the shelf. It is that common. Changing them out is a 2 hour job per side, if you have the right tools. Be sure to replace the originals with quality replacements that have grease fittings and have a tub of anti-seize grease handy, you will need it!