Air Lift air bags are not designed to work with Firestone air spring kits. We do sell replacement air bags for Firestone Ride-Rite kits. Your 2006 RAM 2500 should have Firestone Ride-Rite kit 2299 installed on it. The 2299 Ride-Rite kit uses Firestone replacement air bag 6401, which we sell on our website. If you have any questions, feel free to call us at 1-800-358-4751. All Firestone Ride-Rite air bag kits have replacement air bags available for them and most we have in stock.