I've been noticing that the AC Delco oil and air filters are getting harder to find. Pep Boys, Auto Zone, Western Auto and Advanced Auto (to name a few) Have little or no selection of these filters. Wal Mart has even condensed their shelfs of these products. Some one told me that GM was behind this, in order to get the car owner to the dealer to purchace the filter or have the dealer install them. I have yet to see an AC delco filter for my Duramax on any shelf.