A portable rock crusher and scarifier for in-situ and on-site crushing, milling, grinding and preparation of road beds having a crusher frame defining a crusher channel journaling a reversibly rotatable arbor carrying plural automatically centering tooling implements in symmetrically spaced V-shaped axial keyways and a power pack releasably attachable to a road maintenance vehicle. An anvil weldment channel defined by spaced apart strongbacks communicates with the crusher channel and carries an adjustably positionable anvil weldment carrying two vertically spaced adjacent anvils proximate the arbor. A canting mounting structure provides attachment to a variety of road maintenance vehicles to provide carriage, support and movement. Milling implements may be installed on the arbor for grinding surfaces at depths below the crusher frame, and the crusher frame and power pack may be attached to a base for stationary operation.