having an upper section 42 and a lower section 43 with the upper section 42 and lower section 43 being square or rectangular in cross section the lower section 43 further comprises a protrusion 48 a spacer 45 fits between the upper section 42 and the lower section 43 and is restrained by contact with the protrusion 48 and establishes among other things a length of the vertebral replacement body member 41 the spacer 45 may also increase the overall rigidity of the component 11 help absorb shock during use reduce component 41 wear and reduce the amount of packing material necessary when assembled the spacer 45 may rest on a base 47 of the lower section 43 still further as best illustrated in fig3 the upper sections 12 32 42 52 62 and the lower sections 13 33 43 53 63 of the vertebral body replacement members 11 31 41 51 61 further generally will include a distraction slot 26 36 46 56 66 or similar opening for receiving a distracter instrument 65 or tool therein alignment of the distraction instrument 65 or tool with the distraction slot 26 36 46 56 66 is preserved because of the restriction of relative longitudinal rotation between the upper section.