07/31/2011. Remarks by Johan Visschedijk: "Predecessor of the PT-9 series, this aircraft was a prototype of several versions. Initially produced in 1931 as the Model 6A with an 165 hp Wright J-6 five-cylinder radial engine, it was soon converted to the Model 6D with the 300 hp Pratt & Whitney R-985-1 Wasp Junior nine-cylinder radial.

Subsequently it was redesignated Model 6F when it was re-engined with an 165 hp Continental A-70 seven-cylinder radial and in 1932 it became a Model 6H when fitted with a 210 hp Kinner C-5 five-cylinder radial. Finally it became a Model 6H (and prototype of the YPT-9B primary trainer) when refitted with a 215 hp Lycoming R-680 nine-cylinder radial.

The registration NC786H is presently allotted to another Cloudboy, a Model 6C with c/n 6010."