"We Were The Best There Ever Was." 
One piece of the 511th PIR's history is that there was an actual unit shield used while the unit was stateside during World War II. While not a DUI per se, the blue, green and grey shield to the right was taken from an original jump certificate for a 511th PIR Paratrooper.
The blue was for the infantry, the inverted triangle represented a parachute and the green a DZ.
The more well-known DUI (see below) is a modification of this early shield that was known to the veterans of the 511th PIR from 1943-1945. You can see it on some of the few remaining regimental documents from that era, at least the stateside ones: Jump Certificates, letters home, official notices, etc.
Once the 511th PIR and the 11th Airborne Division as a whole sailed for the Pacific Theater in 1944, use of this crest kind of died off. It was used sporadically during the Occupation of Japan, but more common at that time was the "8 Ball" patches and artwork (see below).
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.
Description/Blazon
A gold colored metal and enamel device 1 5/32 inches (2.94cm) in height overall consisting of a shield blazoned: Per fess nebuly abased Azure and Vert, on a wedge arched in chief Argent, between in base a kris and a Polynesian war club saltirewise and a sun with rays (as depicted on the National Flag of the Philippines) all Or, a torii Gules. Attached below the shield a blue scroll inscribed ""STRENGTH FROM ABOVE" in gold letters.
Originally, this motto was written as "Vigueur DeDessus" which translates to "Strength is From Above," an appropriate motto for Paratroopers.
Symbolism
Blue is the Infantry color, and the blue and green signify the sky and the earth - the nebuly dividing line being the heraldic symbol for clouds. The white, wedge-shaped figure represents a parachute (for airborne infantry) and is also indicative of a wedge being driven from the sky to earth, thus alluding to the regimental motto - Strength From Above. The sun with rays is for service in the Philippines; the crossed kris and war club represent service in New Guinea; the torii symbolizes service in Japan.
Background
The distinctive unit insignia was originally approved for the 511th Airborne Infantry Regiment on 28 Nov 1951. It was redesignated on 6 Sep 1963 for the 511th Infantry.
Description/Blazon
Per fess nebuly abased Azure and Vert, on a wedge arched in chief Argent, between in base a kris and a Polynesian war club saltirewise and a sun with rays (as depicted on the National Flag of the Philippines) all Or, a torii Gules. STRENGTH FROM ABOVE.
Symbolism
Blue is the Infantry color, and the blue and green signify the sky and the earth - the nebuly dividing line being the heraldic symbol for clouds. The white, wedge-shaped figure represents a parachute (for airborne infantry) and is also indicative of a wedge being driven from the sky to earth, thus alluding to the regimental motto - Strength From Above. The sun with rays is for service in the Philippines; the crossed kris and war club represent service in New Guinea; and the torii symbolizes service in Japan.
Background
The coat of arms was originally approved for the 511th Airborne Infantry Regiment on 28 Nov 1951. It was redesignated on 6 Sep 1963 for the 511th Infantry.
