Master Cylinder: 1966-71 era DRUM/DRUM 1" ID - Deep hole * see Notes *

This is a fairly rare master and drum front and drum rear only. READ this details first.  During the later 60's & early 70's while power boosters were NOT mandatory but just and OPTION.. brake masters would be bolted directly to the Firewall.. and your brake pedal Arm had a pin going off it.. as they do.. but this pin went DEEP into the back of the master cylinder so there was buggerall chance of it being miss lodged.   Those with a booster just a dimple on the back of the master and were hard up against the power booster in.   THIS IS THE Master with the DEEP HOLE. NOW.. (don't knodd off yet.....:-)  ) Sometime over the years people have added a booster.. some changed a master too .. but for many THIS MASTER .. with its DEEP approx 1.5 inch hole.. was kept .. and a booster with a long pin was used.    

     It is 1" bore. Has a larger thread at the rear side.. slightly smaller at the front side.   ITS FOR DRUM BRAKES..    NOT DISC.  Used on mainly 67-71 GM passenger cars. Never Disc... but who knows sometimes as custom work done.. however.. remember the main details here.