The Type 65 “Super Coupe” was designed to replace the Daytona Cobra Coupe in 1965. It had a 427 engine, modern suspension and a shape that would theoretically have allowed speeds well over 200 mph. What it didn’t have was a moveable driver-controlled wing at the rear called a “Ring Airfoil” that was initially planned for the Daytona Cobra Coupe.
Had the wing been used on the Daytona it would have been faster, safer and far easier to drive. Once it was “discovered” that the Daytona was unstable at speed without the Ring Airfoil a far less complicated “spoiler” was added to the rear which helped tremendously in improving the Daytona’s performance. Even though the opportunity to fit a Ring Spoiler to the Daytona existed through the 1964 season there was simply no time or opportunity to replace the spoiler and the cars had already proven its superiority over the once invincible Ferrari GTOs. The attitude within the Shelby team was “if it ain’t broke don’t fix it”. Fast enough to win was considered “good enough” without spending more time and money to improve what was already a proven winner.
The Type 65 didn't have a Ring Spoiler because the opportunity to use a “moveable aerodynamic device” on all racing cars had passed by then due to regulations banning them. Others who had adapted moveable “wings” during the interim, like Jim Hall’s Chaparrals and several Formula 1 racers in Europe, were banned when the FIA determined that failures of such devices at high speed would cause a loss of traction and result in crashes that would endanger spectators.