I have just become interested in the transmission codes after my mechanic told me that my '92 Passat AAZ had the wrong transmission in it (!? - I'm the original owner and the transmission has not been replaced...) He believes it is geared much too low, possibly the factory used some gasser transmissions if they ran out of the proper transmission?
I just checked out the code on it and it says CEY, just like yours, but after hours spent searching the internet, I have come up empty handed. If you find any info, please let me know!
News - found some info, had a brain flash and started doing german language searches, it seems that CEY was in fact a correct transmission for the AAZ Passat in Europe, one website said 120 km/hr = 3,000 rpm, which agrees with what I see in my car. I still cannot find a gear ratio chart.