railroad crossing sign

Can anyone help? I have a toy old railroad crossing sign only marking on it is made in usa . it may be an old marx , there is no gate it is just the sign with two bulbs made of metal. there are three wire post in the back can any one tell me how to wire this to my old lionel train set

I don’t know what the three post are and where to wire to to test it? thanks Mike

Welcome.You could be on the wrong forum.At top left hit trains forums and look at the Classic Toy Train site. Joe