There were two engine variants in the D4, 5 cylinder single turbo and 4 cylinder twin turbo, Aisin auto box (as per GM FWD in europe) so pretty bulletproof.
As for the Passat, they always remind me of the Goodness Gracious Me sketch, 'bring me the blandest thing on the menu'
That's the donk. 
Just sorting out getting the box serviced which is a little confusing to get the right information as this car is a 'partial facelift' so I think it needs the AW-1 ATF. Servicing instructions also indicate that it needs VIDA and DICE to reset the adaptations and alter the transmission change counter on the TCM. Doing some research it looks like a lot of owners do a few short distance changes to help get the old fluid out of the system.
This is next job on the Saab, Trying to find the correct grade for the box, isn't easy, as far as I know, it's 3309/aw-1 oil,
Which is approx £100,, for 20L on ebay., Will do a dump and flush, 😕