Hi I just tried the centre headrest from the back of my A4 avant, it does go in the holes on the back of the kombi seat however the notches that allow you to raise it to a specific height are on the inside of the headrest 'legs' of the audi ones and on the outside of the VW ones so basically if you raise it, just falls back down onto the seat again. Hopefully another VW might work for you though.
Have a look here, the part numbers are listedWhich caravelle door cards are people using? Seems to be trendline, comfortline and highline, non have ambient lighting and fabric inserts..