I recently bought a Centex Milling Machine, made in Fort Worth TX. It is current apart awaiting paint and then reassembly. Not long into the teardown process I realized this is basically a Rockwell 21-100 with a different belt drive and motor placement. Everything - base, column, table, handwheels etc is the same as a Rockwell. The difference is in the mounting of the motor and the pulleys. The Rockwell has everything on the front over the spindle, where this Centex has the motor at the back of the machine, and a long belt running to the spindle pulley.
Photos here:
Rex