Heavy armored conveyor junction
Simple realy, i have experienced on many ships that in battle entire turrets fall off.
That is mostly due to the conveyor under them, which they are atached to, are the weakest link in the chain. When they take enough damage they disintregrate, and the weapon atached to it starts to float off in space. Even if the turret itself was still functional and the surounding armor stil strong.
So to build up durability i sugest you make a variant of the conveyor junction that would also include all the components of a heavy armor block, or atleast some of them.