These printers use the C8543X cartridge:
Click On a Printer to View it's Cartridges
          HP LaserJet 9000
          HP LaserJet 9000 DN
          HP LaserJet 9000 HNF
          HP LaserJet 9000 HNS
          HP LaserJet 9000 LMFP
          HP LaserJet 9000 MFP
          HP LaserJet 9000 MFS
          HP LaserJet 9000 N
          HP LaserJet 9000 Series
          HP LaserJet 9040
          HP LaserJet 9040 DN
          HP LaserJet 9040 MFP
          HP LaserJet 9040 N
          HP LaserJet 9050
          HP LaserJet 9050 DN
          HP LaserJet 9050 MFP
          HP LaserJet 9050 N
          HP LaserJet M-9040 DN MFP
          HP LaserJet M-9040 MFP
          HP LaserJet M-9050 DN MFP
          HP LaserJet M-9050 N MFP
          HP LaserJet M-9050 MFP
          TROY-Systems Troy 9000
          TROY-Systems Troy 9050
          TROY-Systems Troy 9050 SECURE
          TROY-Systems Troy 9050 SECURE EX