Complex sentence: This was the first year that the M1 Abrams participated in the competition used by C Company 3-64 Armor of 3rd Infantry Division, stationed in Schweinfurt but the two remaining American tank companies still used the M60A3 Patton tank.
Split into simpler sentences: This was the first year that the M1 Abrams participated in the competition. The two remaining American tank companies still used the M60A3 Patton tank.