RZY,
If you don't feel like taking your tender apart there are alternative tenders that were offered with RailSounds. Two that have come up here in the more distant past, closer to the vintage of your locomotive, are the 6-16655 RailSounds tender, and the 6-19833. These came out circa 1995. More recently Lionel's sold the 6-36788 SteamSounds tender. All of them are designed to replace an existing tender on a conventional locomotive.
Downside? The chuff may not be perfectly synchronized with the turning of the locomotive wheels because there's no electrical connection to a chuff switch in the loco. Instead it's derived from a position/speed sensor in the tender. For some this may be an issue; for others it's part of the "charm".
Mike