I can't say that late AUA and BBY/BAD are incompatible (I have no way of checking physically) because they use the same handle design, but different part number and unclear whether the overall length or position of the wee ball stopper moulded onto the shaft are the same. Certainly early and late AUA would not be able to lock home in each other's guide tubes.
I've had to go back and check the part numbers on 7zap to remind myself. It isn't the sump ; it is the guide tube that changes in the early vs late AUA transition and also BBY to BAD. The early AUA dipstick (8Z0 115 611G) handle has a completely round section with a couple of o-rings that lock the dipstick in place. The late AUA one (8Z0 115 611R) has a pair of hooks and a male v-shaped moulding in handle with corresponding female indentation in the guide-tube end that lock the dipstick home in a specific orientation. Handle design of this is common to the distinct BBY/BAD dipstick (8Z0 115 611P), even though BBY and BAD engines use different guide tube assembly part numbers.
I must admit being a bit confused by the 8Z0115611M part - as it isn't listed in the 7zap pages, but is clearly an FSi part.
See parts 2, 5, and 8 on the following AUA/BBY diagram :
oil container; oil dipstick Audi A2 (A2) 2003 year Audi EUROPA 115045
oil container<br/>oil dipstick Audi A2 (A2) 2003 year Audi EUROPA 115045 spare parts
BAD -
oil container; oil dipstick Audi A2 (A2) 2003 year Audi EUROPA 115020
oil container<br/>oil dipstick Audi A2 (A2) 2003 year Audi EUROPA 115020 spare parts
and for completeness - the Tdi engines
oil container; oil dipstick Audi A2 (A2) 2003 year Audi EUROPA 115040
oil container<br/>oil dipstick Audi A2 (A2) 2003 year Audi EUROPA 115040 spare parts
and finally, some images of each hopefully showing some of the salient differences - not to be taken as accurate scale - just a shame some are in a different orientation. I am having issues with positioning of annotations, so if in doubt go to the thumbnails below as they have the specific part number as image name.
the V-shaped bit on the late AUA / BBY / BAD handle :
late AUA
ANY
and finally, early AUA
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