OEM filter is the Mann 930/21, correct?
You can use either the Wix 51355 or the Purolator L25401.
For some reason, the filter specified changed between the 98-99 and the 00-0x years.
The 98 and 99 models (I don't recall the 2.7T being availible in 98 and 99, but the 2.8 uses the same filter as the 2.7T. the 4.2 uses an entirely diff filter) use the Purolator L30257 or Wix 51191. The only difference I can really discern is that the 98-99 filters are a bit longer than the 00-0x filters, but they have the same thread and very close gasket diameters and bypass settings.
Maybe there is less space on the 00-0x years and thats why a shorter filter is specified in the aftermarket. I do know that the Mann 930/21 filter is specified for all 98-0x 2.8, 3.0 and 2.7T.