So here is what happened.
Another thing on my to do list was to investigate a drive line vibration. I knew the reason had something to do with the front drive shaft. So, I took it to the garage I deal with. We jacked up the car and it turns out that there is a little bit of play in the D30 pinion yoke. It moved up, down, left and right about 4mm !!!
So, he unhooked the front drive shaft off of it, removed the yoke, oil seal, crush sleeve, pinion bearing and checked inside for any damage or anything. Said everything looks fine and started to put the parts back together again.
Now he claims that the pinion nut needs a bit more tightning and this should solve the problem. He cleaned/polished the yoke and the crush sleeve a little bit, put in the new oil seal of course and then kept tightening the damn thing using the impact wrench up to a specific point he had in mind (as he claims) !!!
The vibration is gone and the ride is now a lot smoother than before. But can someone explain to me what did he do and is there anything wrong or scary in what he did???
I'm worried because of all this previous talk about the pinion nut and crush sleeve and how it shouldn't be tight too much