I photographed these Waco YPF examples at Oshkosh and the Western Antique Aeroplane and Automobile Museum (WAAAM) in Hood River, Oregon. There is a very interesting background to this aircraft (one of only two YPF models built) when it was originally tricked out as ordered by the first owner, Miss Connie E. Johnston. More about that can be found in this article.
Second letter “P” indicates open types from 1936
Third letter “F” indicates Tandem cockpit 2- or 3-place open model
The complex WACO naming structure can be found at this link.