Inline tube - PR101 - 64- GM Conversion to Disc / Disc or 4 wheel Disc Brake Proportioning Valve. This is the valve that is sold by all the disc brake companies when you are converting to 4 wheel disc brakes.This is the Disc / Disc prop valve that came on all GM factory disc brake cars. This is exact Inline Tube Reproduction. If you are putting disc brakes on a 64- A/F/X-body or just doing maintenance this item is a must for a correct disc brake car. Dont settle for used parts when comes to your brakes.