Air Tractor AT-500 family
The Air Tractor AT-500 is a family of agricultural aircraft that first flew in the United States on 25 April 1986, manufactured by Air Tractor Inc. Of monoplane low-wing, taildragger configuration, they carry a chemical hopper between the engine firewall and the cockpit.
Source: Wikipedia — Air Tractor AT-500 family (CC BY-SA 4.0)