In 1967 or 68, work was started on a redesign of the Twin Courier in a tricycle-gear configuration for the commercial market, since many firms which desired STOL capability had regulations which required multi-engine aircraft.
The Twin Courier underwent a redesign in the late 1960s, specifically around 1967 or 1968, to accommodate commercial use and incorporate a tricycle landing gear configuration. This was driven by regulations that mandated multi-engine aircraft for companies seeking STOL capabilities.