Item 2901323 has must read information.
: WHEN REBUILDING CYLINDER # 1682243 OR 1682593, JLG RECOMMENDS USING THE SEAL KIT LISTED IN THE PARTS MANUAL PER SPECIFIC MODEL. AND P/N 3480214 PISTON IN PLACE OF THE ORIGINAL COMPONENTS. THE OLD SEAL KIT USED A T-SEAL, THE NEW PISTON USES A LOCK RING AND SEAL. IF THE NEW PISTON P/N 3480214 HAS ALREADY BEEN INSTALLED, THE NEW, UNUSED PISTON CAN BE RETURNED TO JLG.