[Mike_The_Grad]

Well, I finally figured this damn noise out. Center support bearing. Driveshaft grease shield. Different center support bearing mounting location. 6 months of driving= driveshaft grease shield for the center support bearing would rub against the mount for the horseshoe style center support bearing on my truck when the suspension would travel a certain way. The bearing is perfectly fine. Timken brand. About a year old. The rubber support that the bearing sits in is not holding up too well though. It is intact, not cracked, not deteriorated. But it isnt doing a very good job of supporting the bearing. Also I left the original grease shield on the driveshaft when I replaced the bearing. It's a grease shield, what can go bad with that? Well, on the timken brand horseshoe style center support bearing, there are 3 metal tabs that retain the rubber cushion that the bearing rides in. All 3 tabs are located on the bottom half of the support. I'm guessing the pinion angle was off by just enough to allow contact on certain occasions. Which might explain why when I relocated the bearing to the upper location that the noise did not happen as often. Plus it had already made enough contact to establish a wear pattern. How I found this was I thought it might be a good idea to grease the slip yoke right behind the mount. It has been a while since I last did it. But when I was under there, I grabbed the driveshaft and just lifted it and pulled down on it. It seems to have quite a bit of travel. Remembering from previous mounts, and the bad trans fluid and oil leaks I used to have, these rubber mounts dont last long in these conditions. I now remember thinking" timken is good, maybe they outlast other brands in these type situations." Which may be true. I replaced it the same time I had the transmission overhauled along with new u joints. But here I am. The rubber is too soft and is not doing its job of suporting the bearing very well.
Anyways, here is a picture. My pry bar is just stuck in between the grease shield and mount and just hanging there on it's own. Not leveraging it at all.
From the back side there is no indication that anything is wrong at all. But from the front you can see the shiny metal tab and the grease shield now has a flare outwards to it. It didnt used to be like that, from what I can remember.