[2] On the 53rd production aircraft (1963), a swept vertical fin and rudder were incorporated (designated WA.40A; first flying in January 1963 and receiving French certification in March 1963); all subsequent units produced continued the swept design.

In March 1967 the Super 4/21 Prestige, powered by a 235 hp (175 kW) Lycoming O-540 engine.

The 4/21 used a McCauley variable-pitch propeller, autopilot, electric flaps and IFR instrumentation.

[1] An all-metal derivative design, the CE-43 Guépard (Cheetah) was produced by CERVA, a production company which Wassmer and Siren SA formed.

By that time the Guépard offered an optional sixth seat, and designers were developing two further variants, the CE.44 Cougar and the CE.45 Léopard.