In order to meet the demand for mailplanes, Waco aircraft developed two models during 1929, the JYM and the JWM.

It was powered by a 300 hp (220 kW) Wright J-6-9 engine and had a single seat cockpit for the pilot.

[1] The JWM was a straight-wing model based on the ASO, also with a 14-inch longer fuselage and was fitted with a 330 hp (250 kW) Wright R-975 powerplant.

[2] All four Waco JYM's still exist, with the third JYM NC631N on display at the Historic Aircraft Restoration Museum (HARM) at Dauster Field near St Louis, Missouri, wearing its 1929 NWAL CAM-9 route markings.

The sole survivor NX8550 is also preserved at HARM, wearing the markings of the "Art Davis Air Circus".