Jett forks have hangers, Judy and SID forks don't. As of 2000 RockShox no longer produces a cantilever hangered fork. The new dual adjust C3 cartridge can be used in 1997 and 1998 model year forks. It's important to note that Type 3 springs should be used in conjunction with the cartridge to optimize performance and longevity. A prime culprit of leaking cartridges is play in the bushings of the fork.
Excessive play can lead to leaks.
Be sure to check bushing and shaft wear and shaft guides when servicing your fork. This will help to ensure long cartridge life. Corrosion is caused by the introduction of moisture into the fork. This can happen when washing the bike or riding in adverse conditions. Keep your fork clean and dry whenever possible.