Complex sentence: The M107 175mm self-propelled gun was part of a family of self-propelled artillery that also included the M110, the M110E2 chassis had a Depot Level upgraded chassis, drive train due to the heavier "tube" (E2 barrel).
Split into simpler sentences: The M107 175mm self-propelled gun was part of a family of self-propelled artillery that also included the M110. The M110E2 chassis had a Depot Level upgraded chassis and drive train due to the heavier "tube" (E2 barrel).