clicking/clunking sound from rear

[splmark]

I'm not sure what is making the sound but its the loudest driving slowand when I take my foot off the gas. Everyone told me its my u joints but I changes them and that's not it. What else should I look at

 

[JohnnyO]

Clean and lube the slip yoke where the driveshaft connects to the tranny or t-case.
If that doesn't fix it then you likely have problems inside the differential.

 

[splmark]

When I did the u joints I checked the slip yoke it had alot of grease. I'm going to clean it and put more in tomorrow and see if that helps