89Crown

I have a 1989 Crown Vic with about 48,000 miles on it. When I went to release the parking brake last week, the brake light remained illuminated. I still had brakes, but it feels like the brake pedal is pulling on the E-brake cable and brake pressure is minimal. I found a leak in the brake line on the passenger side of the master cylinder. There is a crack all the way around a nut that connects the master cylinder to the brake line.

I have had one person tell me this is a proportioning valve but this does not make sense because there is only one input and one output to the valve. For it to be a proportioning valve, there would have to be a separate valve for the other set of brakes, either front or rear. I have also tried to find this part, but the dealership has quit making it and it is not included in the master cylinder assembly that you would purchase at an auto parts store.

Does anyone know what exactly this part is? If it is a valve, I have a problem since I found a Master Cylinder with this additional port for $300 as opposed to $110 for the Master Cylinder from either Napa or CarQuest.

Any help would be great.