[Vwdiesel] A2 strut insert question

[Scott Kair]

    Somewhere along the line I tripped over a notation that some A2 front
struts were sealed units which had to be replaced completely rather than
merely by replacing cartridges.
    Bentley doesn't mention this, and I'm wondering if I got some bogus
information on the sealed units.  What has me wondering is that the strut
case on my 92 Jetta carries a Boge number (1-0691-27-A58-O).  I've never
seen numbers on a strut case before, but then the ones I've seen before were
all fairly rusted.
    Any encounters with sealed units?
    TIA,
    Scott Kair