Mopar disc drum proportioning valve / distribution block. If this is the case you will need to tap the stud out of the bracket that is included on the valve. Fits a,b,c and e bodies from 1960-74 with disc front & drum rear.
Universal Black GM Disc Disc Brake Proportioning Combination Valve 4 Wheel Disc
Disc Disc Brake Proportioning Valve 9/16" 1/2" Lines & Bracket PV2 Combination
Chrome Disc Disc Brake Proportioning Valve 9/16 1/2 Lines + Bracket impala nova
Disc brake proportioning valve 4 wheel disc pv4 mounts below GM master cylinder
Disc Disc Brake Proportioning Valve 1964-1972 For Chevrolet Chevelle 172-2215