Can someone tell me about this hallmark?

Hello,
My mother-in-las and I purchased this great Racine Silver Plate and Rockford Silver Plate condiment caddy. It has etched glass salt and pepper shakers, oil and vinegar viles and a sugar container. Beautiful piece. But we are curious about the hallmark and history of the piece.

What does the 366 mean? Around what year? And what is the value?

Thank you.