Here are some other O-scale MARS lights:
Top of picture is the prototype. (photo removed 8/18/19) You can see the side to side motion of the light. I was using it to set the timing of a 555 timer fade/throb LED circuit I breadboarded (bottom of picture).
555 circuit installed in a 90s Lionel PA-1
Lionel Legacy F3
The best of the bunch is the Atlas Erie-builts using dual fade/throb bulbs to simulate the side to side motion. The Ngineering product has a similar effect.
Bob