A support block for a steam turbine casing, a related assembly and apparatus. Various embodiments include a steam turbine casing support block having: a body portion sized to substantially fill a pocket in a steam turbine casing, the body portion having a greater length than a depth or a width; a set of tabs extending from the body portion, each of the set of tabs sized to substantially fill a corresponding slot in the steam turbine casing, wherein the set of tabs are located at a radially outwardly facing wall of the body portion; and a pin hole on a bottom surface of the body portion for receiving a retaining member.