Clunk noise when shifting upwards

One other thing to check, as long as you are looking, would be to make sure the pinion nut is torqued. You have to unbolt the the rear u-joint and drop the rear end of the drive shaft out of the way to get to the pinion nut.
Mine came loose just a few weeks ago and the ring & pinion gears got chewed up a bit as a result and I had to overhaul my center section.
Just another thing to check...