Well, it wasn't the u-joints. Took off the driveshaft since I couldn't get my grease gun on the Zerg fitting - re-greased and re-installed. Still makes the noise.
I did notice that it doesn't seem to do it in first gear from a stop. Only when going from one gear to the next while moving. It definitely makes the squeal for 2-3 seconds after the clutch has been fully released. So, unless there is significant slipping of the clutch, I don't think it is the pilot bearing.
So I guess I'm back to the pipe. I guess it could be clutch or transmission, but it sounds like it is coming from the pipe.
