Although pilot Quatre Raberba Winner had activated the self-destruct system on his XXXG-01SR Gundam Sandrock during his escape into space, the ensuing explosion had rendered the mobile suit useless - but its gundanium alloy body was still more or less intact. The Sandrock's remains were be confiscated by OZ, but later would be retrieved by members of his Maganac Corps allies and taken to their underground base in the Middle East, where it would be rebuilt and fully restored. After Quatre's return to Earth, he returned to the Maganacs to pilot his Gundam once again. But the military and political strife plaguing the Earth Sphere in AC 195 would reach a decisive conclusion in space, and Quatre returned to space with his Sandrock to join the battle. Aboard the independent battleship Peacemillion, Gundam supporter Howard would upgrade the mobile suit, giving it minor improvements for space combat.

Though the changes made to the Gundam Sandrock Kai were cosmetically minor, they would give the mobile suit the edge it needed to use its abilities against the spacebound forces of White Fang's Virgo II mobile dolls and the mobile suits of the World Nation military. The addition of several vernier thrusters made the Sandrock stable to operate in a zero-gee environment. In additon, the Gundam Sandrock Kai sports a much larger pair of heat shotels, now mounted on special booster units attached to its backpack. Other optional accessories include a protective cloak, and a revamped shield which lets the Sandrock Kai form its trademark "cross crusher." Also, over Quatre's protests, Gundam pilot Heero Yuy also temporarily outfitted the Sandrock with a component of the XXXG-00W0 Wing Gundam Zero's infamous Zero System, allowing Quatre to coordinate the Peacemillion's mobile suit forces in a major assault against White Fang's mobile dolls.

Source: Gundamproject.com, Gundam W: Endless Waltz DVD