Staff Writer (Updated: 7/3/2016):
The "Kaydet" was initially received by the United States Navy in the form of the Model 73 production series and designated as the NS-1 produced in no fewer than 61 delivered examples. The Model 75 was derived from this production model which was then accepted by the United States Army as the PT-13. These versions were fitted with a Lycoming R-680 engine of 215 horsepower output. 2,141 PT-13 examples were produced and this in five subvariants (PT-13 followed by A, B, C, and D models). Further development led to increasingly improved versions of the base Model 75 that featured a host of powerplant and instrument changes. Kaydets were now being produced on orders numbering thousands and included a slew of USN and US Army variants differing mainly in engine types installed.
Introduction of the Continental-brand R-670-5 series of engines led to a new designation as the PT-17 of which 3,519 were produced (across A- and B-model variants). Later models produced with a Jacobs R-755 powerplant were further designated as PT-18's and these numbered 150 units. The Boeing-Stearman design was also sold to Canada under Lend-Lease during World War 2 as the PT-27 (with enclosed cockpit) and numbered 300 examples delivered.
Total production of Model 75 was approximately 9,800 units.
The Canadian Lend-Lease Model 75s were called "Kaydet" and the name stuck over time, still being used today to identify the line. Kaydets managed to see considerable use after the war as well in the aerial acrobat role and crop dusting. Operators spanned the globe from Argentina and Bolivia to the Philippines and Venezuela (see operators listing below for complete global reach).
Taiwan (Republic of China) was another wartime Lend-Lease partner and recipient of the Kaydet.