vibration

Hope someone can help me out, I have a really bad vibration through my truck which it has had since the day I picked it up 1 year ago. Only happens when you are on the throttle, it's so bad that the gear stick vibrates that much it sounds like you are constantly grinding a gear. You feel it through the clutch, floor and seat. The stick even rattles when just cruising but as soon as you let of the fuel it goes away. It does it in every gear and not at a certain speed. Also you can hear a really loud rattling from out side with the window down which to me sounds like it is coming from the gearbox or sounds like gears rattling together. It also does it worse when the truck gets hot. I think the noise is coming from the gearbox but I keep being told that it is impossible.
It's in a Kenworth with an isl an an eaton 9LL. It has had 2 new clutches, new flywheel, balanced drive shafts, balanced pto shaft all of the repto gear lash checked end play measured and so many cut out test I can't count them. Me, Kenworth and cummins are all at a loss.

One thing I found though when I was greasing it today was the front engine mount seems to have a large gap at the bottem and I was wondering if this is normal I can't remember and don't have any of my other trucks anywhere near me at the moment.

Here is a video of the gear stick

[video]http://i1109.photobucket.com/albums/h439/yw84u1/A35B270C-5BFA-48D8-8DBB-4F1369C822CE-1815-000000FFA38A10F9_zps98229f3b.mp4[/video]

And the engine mount

 

Yeah I will get them to check it out, had a look at my other trucks same models and engines a 2 have a gap as well but no where near as big and one didn't have one so I don't know.

The vibration has slowly gotten worse over the last year at the start it would really only happen in the top side of the box but now it happens in every gear you can even feel it as you are dropping the clutch starting off but gets worse the more you out your foot down. It that movie it wasn't even that bad but it lost a lot of quality when I uploaded it so it doesn't sound that bad