During the 1960s and 1970s, Rolex received exclusive orders to create specific timepieces for various military organizations and air forces, such as the Peruvian Air Force (Fuerza Aérea del Perú "FAP") for their pilots. These tool watches were often modified to meet specific requirements, and in some cases, high-ranking members of these organizations were provided with specially ordered Rolex watches. These modified timepieces would feature engravings of issue numbers on the caseback and sometimes the whole or partial case number on the inner caseback.

The present reference 6265 is one such special issued watch with a correct 3-million range serial number. It is distinguished by the engraving of the last three digits of the case number "866" on the inner caseback. Notably, there is a small hole on the outer caseback near the "teeth", as seen in examples of Rolex engraved casebacks. This hole was used to secure the caseback while Rolex engraved the markings. However, the present caseback does not contain any engravings, which could possibly be due to the fact that this particular example was initially intended to be delivered to the military but was cancelled and sent to the civilian market.

It is remarkable that this watch has been well-preserved and retains its original case proportions, correct early bezel, crown, and pushers. This example circa 1973 belongs to the earlier productions of the reference 6265, and it features the rare "Sigma" symbol at 6 o'clock, indicating the use of precious metal on the indexes. Adding further to its rarity, the "Rolex Oyster Cosmograph" signature is positioned farther from the crown in these earlier examples.