Information Source:
https://www.nationalmuseum.af.mil/Visit/Museum-Exhibits/Fact-Sheets/Display/Article/196263/north-american-p-51d-mustang/

The Mustang was among the best and most well-known fighters used by the U.S. Army Air Forces during World War II. Possessing excellent range and maneuverability, the P-51 operated primarily as a long-range escort fighter and also as a ground attack fighter-bomber. The Mustang served in nearly every combat zone during WWII, and later fought in the Korean War.

(MUSTANGS FOR THE USAAF)
In March 1942 the USAAF accepted the first production P-51A fighters. Although excellent at lower levels, the P-51A's Allison engines severely limited performance at high altitude. The USAAF employed P-51As in the China-Burma-India theater, where most combat took place at low altitude.

AG1 -
AG2 - Landing Light
AG3 - Opens Canopy Window
AG4 - Opens Canopy
AG5 - Pylons (Drops bombs/tanks if added)
AG6 -
AG7 -
AG8 -