GM Part Number: 986537 WINDSHIELD WASHER - FOOT OPERATED

This style was a GM truck accessory prior to 1954.

Here are 5 illustrations/photos from Denny Graham's photo album.

Obsolete Chevrolet Parts supposedly sells them?

Another listing - same vendor?

They show 51-53, but I think it was the same from 49-53. A unit with a different style jar was supposedly available in earlier years.

Random photo from a web search.