An adjustable width mold apparatus for a slip form paver, the mold apparatus comprising: a center portion terminating in left and right lateral ends (48, 50); a left sideform assembly including a laterally inner end; a right sideform assembly including a laterally inner end; a left adjustable width support assembly including a laterally outer end connected to the left sideform assembly and a laterally inner end connected to the center portion and extending laterally inward of the left lateral end, the left adjustable width support assembly including a left actuator for extending and retracting the left adjustable width support assembly; a right adjustable width support assembly including a laterally outer end connected to the right sideform assembly and a laterally inner end connected to the center portion and extending laterally inward of the right lateral end, the right adjustable width support assembly including a right actuator for extending and retracting the right adjustable width support assembly; one or more left side spacers configured to be received between the laterally inner end of the left sideform assembly and the left lateral end of the center portion, such that when the left adjustable width support assembly is retracted a laterally innermost one of the one or more left side spacers is held directly against the left lateral end of the center portion; and one or more right side spacers configured to be received between the laterally inner end of the right sideform assembly and the right lateral end of the center portion, such that when the right adjustable width support assembly is retracted a laterally innermost one of the one or more right side spacers is held directly against the right lateral end of the center portion, characterized by a plurality of left side hanger rods extending between the left sideform assembly and the center portion, the one or more left side spacers being configured to be received on the left side hanger rods between the left sideform assembly and the center portion; and a plurality of hydraulic nuts (276A-276D), each hydraulic nut (276A-276D) being attached to a respective one of the hanger rods and configured to apply a clamping force to clamp the one or more left side spacers between the left sideform assembly and the center portion. a center portion terminating in left and right lateral ends (48, 50); a left sideform assembly including a laterally inner end; a right sideform assembly including a laterally inner end; a left adjustable width support assembly including a laterally outer end connected to the left sideform assembly and a laterally inner end connected to the center portion and extending laterally inward of the left lateral end, the left adjustable width support assembly including a left actuator for extending and retracting the left adjustable width support assembly; a right adjustable width support assembly including a laterally outer end connected to the right sideform assembly and a laterally inner end connected to the center portion and extending laterally inward of the right lateral end, the right adjustable width support assembly including a right actuator for extending and retracting the right adjustable width support assembly; one or more left side spacers configured to be received between the laterally inner end of the left sideform assembly and the left lateral end of the center portion, such that when the left adjustable width support assembly is retracted a laterally innermost one of the one or more left side spacers is held directly against the left lateral end of the center portion; and one or more right side spacers configured to be received between the laterally inner end of the right sideform assembly and the right lateral end of the center portion, such that when the right adjustable width support assembly is retracted a laterally innermost one of the one or more right side spacers is held directly against the right lateral end of the center portion, characterized by a plurality of left side hanger rods extending between the left sideform assembly and the center portion, the one or more left side spacers being configured to be received on the left side hanger rods between the left sideform assembly and the center portion; and a plurality of hydraulic nuts (276A-276D), each hydraulic nut (276A-276D) being attached to a respective one of the hanger rods and configured to apply a clamping force to clamp the one or more left side spacers between the left sideform assembly and the center portion.