An air delivery system (210, 310) for a farm machine having an exhaust duct (262, 362) configured to receive exhaust (261, 361) from an engine (220, 320), the air delivery system comprising: a first rotary blower (250, 350A) including a housing and having a first rotor and a second rotor rotatably disposed in the housing, the first and second rotors having meshed lobes for transporting air from an inlet port to an outlet port, the first rotary blower further including a first rotor shaft and a second rotor shaft rotatably supported by the housing and having the first and second rotors, respectively, fixed for rotation therewith; a first aftertreatment enclosure (254A, 354A) configured to receive and surround a first portion of the exhaust duct (262, 362) and having a first inlet, a second inlet, a first outlet, and a second outlet (278A, 378A), wherein the first inlet receives the engine exhaust (261, 361) from the engine (220, 320) and the second inlet receives a first portion of cooling air from the first rotary blower (250, 350A) to reduce a temperature of the engine exhaust (261, 361) passing through the first aftertreatment enclosure (254A, 354A), wherein the engine exhaust exits the first aftertreatment enclosure through the first outlet, and the cooling air is vented to ambient air through the second outlet (278A, 378A); and a second aftertreatment enclosure (254B, 354B) configured to receive and surround a second portion of the exhaust duct (262, 362) and having a third inlet, a fourth inlet, a third outlet, and a fourth outlet (278B, 378B), wherein the third inlet receives the engine exhaust from the engine and the fourth inlet receives a second portion of cooling air from the first rotary blower or a second rotary blower to further reduce a temperature of the engine exhaust received from the first aftertreatment enclosure (254A, 354A) and passing through the second aftertreatment enclosure (254B, 354B), wherein the engine exhaust exits the second aftertreatment enclosure through the third outlet, and the second portion of cooling air is vented to ambient air through the fourth outlet (278B, 378B). a first rotary blower (250, 350A) including a housing and having a first rotor and a second rotor rotatably disposed in the housing, the first and second rotors having meshed lobes for transporting air from an inlet port to an outlet port, the first rotary blower further including a first rotor shaft and a second rotor shaft rotatably supported by the housing and having the first and second rotors, respectively, fixed for rotation therewith; a first aftertreatment enclosure (254A, 354A) configured to receive and surround a first portion of the exhaust duct (262, 362) and having a first inlet, a second inlet, a first outlet, and a second outlet (278A, 378A), wherein the first inlet receives the engine exhaust (261, 361) from the engine (220, 320) and the second inlet receives a first portion of cooling air from the first rotary blower (250, 350A) to reduce a temperature of the engine exhaust (261, 361) passing through the first aftertreatment enclosure (254A, 354A), wherein the engine exhaust exits the first aftertreatment enclosure through the first outlet, and the cooling air is vented to ambient air through the second outlet (278A, 378A); and a second aftertreatment enclosure (254B, 354B) configured to receive and surround a second portion of the exhaust duct (262, 362) and having a third inlet, a fourth inlet, a third outlet, and a fourth outlet (278B, 378B), wherein the third inlet receives the engine exhaust from the engine and the fourth inlet receives a second portion of cooling air from the first rotary blower or a second rotary blower to further reduce a temperature of the engine exhaust received from the first aftertreatment enclosure (254A, 354A) and passing through the second aftertreatment enclosure (254B, 354B), wherein the engine exhaust exits the second aftertreatment enclosure through the third outlet, and the second portion of cooling air is vented to ambient air through the fourth outlet (278B, 378B).