Marx produced two lighted cabooses in 6" tin.
from 1939 - 1942, with fixed tab/ slot coupler, the prewar NYC #556...
and in 1953 for separate sale only, NYC #20102...
sometimes faked by swapping a lighted passenger car frame, note the rivets holding the window strips which is a detail often overlooked. the lighted #20102 also sports a #556 style cupola rather than the standard #20102 version. have never heard of an explanation for that oddity.
i have seen activation switches on either side, but do not know if one of more common. as you can see, the #556 i have has a right (starboard) side switch, while the #20102 switch is on the left.
cheers...gary