The RGM-79 GM Custom is an improved version of the standard mass-produced GM, only a small number of these units were fielded late in the war. One such unit is piloted by Sayla Mass.
Technology & Combat Characteristics
A custom RGM-79 GM with reinforced armor to increase its durability. Its performance exceeds that of the regular production GM, and is implied to possibly be on par with that of the Gundam. In addition to improved armor, this mobile suit is able to carry more grenades, and is equipped with 2 beam sabers instead of the standard GM's 1. Like the Gundam following its refit at Jaburo, the GM is equipped with a "Core Pod" escape craft.
Appearing in Vol. 21 of the Mobile Suit Gundam: The Origin, this improved variant of the RGM-79 GM is a high-performance variant for ace pilot, equipped with additional armor and weapons including grenades and a second beam saber. Only a small number of these machines appear to have been produced, one of which is piloted by Sayla Mass, one of the crew members of the legendary White Base. Though she had prior experience piloting a Core Fighter and Core Booster, the Battle of A Baoa Q was the first time Sayla sortied in a mobile suit. Despite this, she performed very well, at one point defeating a Braw Bro with apparently little effort. Such was the performance of the GM and Sayla's skill in its use that the Braw Bro's pilot, shortly before his defeat, erroneously assumed his opponent to be the infamous "Fed Newtype" Amuro Ray.
Sayla's GM was severely damaged in combat, and she abandoned it - escaping in the Core Pod, which landed on A Baoa Qu. At least one additional unit of this model appeared among the Federation Forces that landed on A Baoa Qu and engaged the defending Zeon forces in the fortress itself.