A Boeing 'Stearman' PT-17 (Model 75) owned by Warren Walkinshaw, Argusville, ND. Photo by Bob Nelson

After World War II, the thousands of PT (primary trainer)-17 Stearmans were auctioned off to civilians and former pilots. Many were modified for cropdusting use, with a hopper for pesticide or fertilizer fitted in place of the front cockpit. Additional equipment included pumps, spray bars, and nozzles mounted below the lower wings. A popular approved modification to increase the maximum takeoff weight and climb performance involved fitting a larger Pratt & Whitney R-985 engine and a constant speed propeller. -wiki