G-8Y5 was an engineering droid on Uffel. QS-2D considered G-8Y5 its greatest creation, better than its model of war droids or the single droid that controlled (or "was") the entire spaceport of X2-4 City.
G-8Y5's role was to upgrade Uffel's droids and keep them in working condition, and also to develop new droid types. G-8Y5 developed Uffel's space weapon platforms, who saw first use when defeating a pirate attack in 33 BBY. It could have played a large role in developing the MSF-series mouse droids and Uffel's advanced war droid defenders. G-8Y5 developed many prototype droids, some of which were sold to buyers elsewhere in the Cularin system. Many owners of strange droids claimed that they were from Uffel, but that was not always true.
G-8Y5 worked along with 4-KT in droid design.