Yikes, trying to get through emissions here in AZ. They need to run the rear wheels on a dyno and so the rear drum brakes need to be strong enough to brake against the dyno. Weak rear brakes is a common problem according to the tech on our dents. Well when looking over my brake system, I noticed that the proportioning valve right below the master cylinder had a leaky pressure switch on it. I tried to tighten it but found out that it was already cracked and seemed to be of plastic construction! One brake line broke when I tried to take it off with my flare wrench so now I need to go with at least one new lines. I would like to take this opportunity to switch over to a late model valve from a rear disc brake truck and buy some caliper brackets and convert to rear disc brakes since I will be making new lines anyway. If I do go this way what year/model proportioning valve would be a good part to use for my dent? Is there any valve out there that will bolt right on to my truck? I understand I need a pair of caliper brackets and rotors/calipers from a 77 K series Chevy. Thanks for your help in advance, Roy