While the original World War II-era DUI never materialized into a Shoulder Sleeve Insignia (SSI), during the later Occupation of Japan and while the 511th AIR was at Fort Campbell, the SSI to the right was indeed used and can be seen into photos into the 11th Airborne Division's Gyroscope-induced movement to Germany.

I am still researching where the decision to use an "8 Ball" to identify the 511th's well-known Paratroopers, but it doesn't surprise me given the young troopers' reputations from 1943 through the regiment's inactivation in 1958. Highly effective in combat, but hell-raisers when not.