Both Legacy and FlyerChief operate with constant voltage on the track. The Legacy engine ignores the FlyerChief commands and vice versa. Both can run on the same track in command mode independently responding only to their own signals.
All the engines you have will work in conventional mode with a transformer, but each will run in response to the track voltage, not independently.
The difficulty of converting a Lionel AF Geep depends on which motor it has. All recent production Lionel AF use DC can motors. I send mine to a professional to convert but many of the more skilled operators here do it themselves. Interoperability of Legacy and FlyerChief with the same remote is not currently possible in S gauge although it can be done in O gauge using Bluetooth. The reason is that the newer FlyerChief engines have Bluetooth but no S gauge Legacy engines have Bluetooth. Lionel made a decision to include DCC capability in S gauge rather than Bluetooth. In any event any engine you convert will be TMCC which needs a Legacy controller (or a conventional transformer), there is no Bluetooth option with TMCC.
Both Legacy/TMCC and FlyerChief can be run from an iPhone using an App, but they are separate apps so you need to toggle between them. In S gauge this requires an LCS WiFi module for pairing with the iPhones.
