I just checked HP's site, and there does appears to be only one print driver available for download. Now, a couple things that I may suggest, is that you try and update the firmware for both the Printer and the Jet Direct Card (Network Card). I have seen a couple of HP's models have issues printing PDF files, that have been resolved by a firmware update. Hope this helps.
Timothy N. Couch
A1 Printech
Anchorage, AK