Welp, as the title says, my drive shaft is extremely hot. as well as the front of my rear diff. I know this cause I had to pull my drive shaft ( I have a double cardane with an SYE) because of a bad vibration that turns out to be ( I think) a bad rear ujoint. After removing the drive shaft I also found a seized slip yoke. Not good. I spent an hour hammering that damn thing apart. Yes I greased it, like a year ago. lol. Once apart it looks like the spline coating is melted. Which could be possible since it was hot to the touch when I removed it. Pinion bearing seems OK. I haven't checked the diff oil today but I did recently. I will check it tomorrow. The exhaust was hot and I had only driven it a few miles prior to removing the DS. My questions are, Could my Cat be plugged causing the exhaust to heat up and also heating up the DS? Did the DS get hot enough to melt the spline coating and cause the slip yoke to seize causing the ujoint to fail. Or did the ujoint fail and the vibration cause slip yoke to heat up??? Or, captain obvious, it failed from a lack of lubrication???