Date: 1934. Owner unknown
The Pan American 64B Slender Model has a #1 (0.438") bore and was produced between 1931 and roughly 1948. Notice that the design of the instrument is similar to the New Era models (10B, 56B, 58B, 60B).
The name "Frat" model appears in a 1935 catalog from the Fischer music company. There is every reason to believe that the names, pictures and descriptions are the same as they would appear in Pan American publications from 1935. The 1938 Pan American brochure doesn't have that name with the 64B, so perhaps it was dropped at some point.
What Pan American said in 1935:
The "Frat" model is a masterpiece in design and construction. It is modern in its long, slender lines. It has the true trumpet tone - brilliant, vigorous and of great carrying power.
20 inches long - 4¼ inch bell. Weight 2 pounds.
64-B-4. Polished brass
64-B-2. Satin silver, gold bell
What Pan American said in 1938:
Features "Slik-Valves" for greater playing ease, speed and longer life. Fine tone, true scale, easy action. Built in Bb and A. Length is 20 inches.