Hi Michael,
I have some bottom gated skillets and griddles like that one. There were several, perhaps many different makers of very similar skillets and griddles. Very few of them were marked.
They look almost alike at first glance, but when you get them side by side to compare, you can see some different features.
I have one that looks the same in almost every detail to a marked Excelcior, but it is not marked. I call it an unknown along with the rest of them. The only griddles I would consider to be Excelcior would be ones that bear their mark.
Chris