Thank you Tristan. Yes the axles n differential were removed long time ago. I was changing my axles from one piece type to two pieces type(anular??) so it took me awhile to figure out what would fit.

Anyway, looking at the last 2 pics from whunter's post, I can see that the female part on the end of the front shaft has 3 cuts and the big nut is used to close these 3 gaps. When the gaps are not closed that's when we get vibration. And that's why we mark the location of the turning of the nut. Is that wrong??? Other than that I can't see the reason since everything is symeyrical.