bechmads

Hi all, thanks for letting me trouble you with this issue.

A friend of mine has a E220 diesel 9g-tronic Estate with about 135.000 miles on it and is experiencing intermittent shaking/twitching while driving, almost like a misfire or something in that direction.
We went for a drive for almost 1 hour and it began to occur about 25-30 minutes into the drive starting of not being so bad and increased in "strenght".

There is absolutely nothing to be heard when the engine is idling or on rapid acceleration, only appears on light acceleration or cruising above 40-50 mph with or without the ACC.
The car has always been serviced by authorized MB workshops and therefore he brought the car there for them to make a diagnosis.

In the beginning they said it was the tourque converter but after 30 hours of diagnosing(they say) ended up saying it needs a new cylinder head(no evidence or explanation for this conclusion)?
I told him to try another specialist with a good reputation and so he did.

Their conclusion was that the torque converter was bad and needed replacement but recommended replacing the entire transmission, honestly it sounds like BS to me?
There is no slipping in gears, no judder from the converter and no other evidence pointing towards a defect in the transmission.

I'm a mechanic myself and have been for 10 years working on Volvo Trucks, Volvo construction equipment and my own cars with a few exceptions.
I don't know about MB procedures at the authorized workshops but when I rarely doom an engine or a transmission i'm required to do a lot of documentation which niether workshops can provide?

But I'm really struggeling to get to the cause of this, so I'm wondering if anyone ever tried the same?

Thanks in advance.