I was driving down road when I heard a clanking noise coming from back of truck. I was going about 26mph and I checked for warning lights and system info that shows Temps, but everything was showing normal. The noise got louder ,so I took foot off gas pedal, which then started getting a loud rubbing noise coming from wheels. Truck slowed down quickly. When I pressed gas pedal the clanking/grinding noise got louder. I was close to a 7-Eleven entry way,so I took foot off gas. I then heard a loud clanking (like metal dropped on pavement), so I turned to enter 7-Eleven area to get truck out of road . Truck turned into entrance and came to a dead stop. No of pedals were pushed, engine was in drive, and noise got louder. I turned off truck, cause of noise and dashboard had most lights on adif you were going to start engine. There were no red warnings or messages showing on dashboard. With engine off, I got out of truck and looked under my truck and the rear driveshaft was completely off sitting on road, and the rear transmission joint it connects to was dumping transmission fluid onto pavement. Fluid was bright green with nothing in it. The truck would not move, all 4 wheels were locked up. Me and several people tried pushing truck so the rear end was in roadway. Put truck would not move at all. If you turned key to put into neutral the clanking/grind noise would start again so shutdown engine. I called roadside assistance to come tow truck to dealership a few miles from