B5.5 Passats have a different glow plug system than other TDIs. They have four individual wires instead of an intact harness. But like the Jetta/Golf/New Beetle with the PD engines, VW had mandated a change from ceramic to steel glow plugs.
You can use this kit to both renew the wiring to your glow plugs as well as replace your ceramic plugs with steel ones. It includes four wires and new steel glow plugs, both from VW.
Switching to steel glow plugs requires an ECU re-flash. Your local VW dealer may be able to perform this service, and there are tuners who can also re-flash your ECU for the steel plugs. It's essential that you re-flash the ecu before installing the steel glow plugs.