Lionel put a whistle into the little lithographed sheet metal station in 1937 and numbered it the 48W. The station was originally sold in green litho with a transformer in it with the Winner line.
The 48W allowed kids with trains that didn’t have whistles to add whistles to their layouts. This was a cheaper option than buying an extra tender with a whistle.
The box for this station is rarer than the item itself. The box is just flimsy cardboard and didn’t survive.