Model 40
Original 1925 design with Liberty engine.

Model 40A
Revised 1927 design for BATC.
the aircraft was powered by a Pratt & Whitney Wasp radial engine, plus seating for two passengers in an enclosed cabin; 25 built.
Received Dept of Air Commerce Approved Type Certificate #2.

Model 40B
Model 40As re-engined with a 525 hp (391 kW) Pratt & Whitney Hornet radial piston engine.
19 Model 40A were converted.
Redesignated Model 40B-2.

Model 40B-4
Revised Model 40B with seating for four passengers and other improvements.
 Equipped with openable windows, plus seating for four passengers; 38 built.

Model 40B-4A
One Model 40B used as engine testbed by Pratt & Whitney.

Model 40H-4
Four Model 40B-4s built by Boeing Canada.
Two aircraft were exported to New Zealand.

Model 40C
Similar to Model 40B-4 but with Pratt & Whitney Wasp engine of Model 40A. (ten built, all later converted to Model 40B-4 standard).

Model 40X
Unique special-order machine similar to Model 40C with only two-passenger cabin and extra open cockpit forward of pilot's cockpit.

Model 40Y
Unique special-order machine similar to Model 40X, but with Pratt & Whitney Hornet engine.
Model 40
Original 1925 design with Liberty engine.
Model 40A
Revised 1927 design for BATC. the aircraft was powered by a Pratt & Whitney Wasp radial engine, plus seating for two passengers in an enclosed cabin; 25 built. Received Dept of Air Commerce Approved Type Certificate #2.
Model 40B
Model 40As re-engined with a 525 hp (391 kW) Pratt & Whitney Hornet radial piston engine. 19 Model 40A were converted. Redesignated Model 40B-2.
Model 40B-4
Revised Model 40B with seating for four passengers and other improvements.  Equipped with openable windows, plus seating for four passengers; 38 built.
Model 40B-4A
One Model 40B used as engine testbed by Pratt & Whitney.
Model 40H-4
Four Model 40B-4s built by Boeing Canada. Two aircraft were exported to New Zealand.
Model 40C
Similar to Model 40B-4 but with Pratt & Whitney Wasp engine of Model 40A. (ten built, all later converted to Model 40B-4 standard).
Model 40X
Unique special-order machine similar to Model 40C with only two-passenger cabin and extra open cockpit forward of pilot's cockpit.
Model 40Y
Unique special-order machine similar to Model 40X, but with Pratt & Whitney Hornet engine.
Boeing Model 40