An adjustable width mold apparatus for a slipform paver includes a center portion and left and right sideform assemblies. The center portion has left and right lateral ends. Left and right adjustable width support assemblies are connected between the sideform assemblies and the center portion. One or more spacers may be received between each sideform assembly and the center portion to adjust the width of the mold apparatus. The spacers may be hung on a plurality of hanger rods. Each of the hanger rods may have a hydraulic nut on one end thereof for clamping the spacers between the sideform assembly and the center portion.