The original 154 has 3 contacts and uses a special 154C that is only compatible with tubular track.
As you see, there are 3 contacts.
1 - Common Hot
2 - Lamp Ground
3 - Other Lamp Ground
If you search the forum, you can find custom flasher units that can work with a simple Fastrack Insulated Rail activation section.
https://ogrforum.com/t...g-for-a-154-crossing