Okay so I thought that I had a bad U joint. I was out in -20 weather and when the car is under load it was fine, but between shifts or if coasting there was a strange shake. The other night that strange shake turn into OMG WTF level of shake not under load. Took the car in put it on the lift no play at all in the drive shaft, and this morning it was back to the strange shake not the OMG WTF shake. The only difference is today it was above freezing, and when it felt like the drive shaft was going to come through the floor it was -20. Bad CV axel? or bad diff?