This just started about a day ago but whenever I turn to the right I get one clunk that I can hear and feel. It's coming from th back right of the truck. My first thought was that it's the dif but I'm not sure. Any other ideas?

 

No ideas except crawl under and inspect.

 

Two things, could be the slip yoke needs greasing on the drive shaft, but if you Have limited slip differential, you could have a clutch pack going bad.