Treadle Valve issue

Well, I found and fixed the problem today. The troubleshooting material I got on line pointed at 1 of 2 two way check valves being bad. So, I started looking for the two way check valves and came up empty. I thought that maybe the check valves were incorporated (built in) into another device. I noticed a big valve on the firewall of the truck adjacent to the instrument panel where I had heard the leak the previous day and it had a 6 airlines and two pressure switches hooked to it. The truck almost never sees any bob tail use but the last time I bob tailed with it (about 6 months ago) I remember the braking was poor on it. Not very good at all.. That was weird to me. I could'nt find any numbers or names on the valve at all so I took a picture of it with my phone and headed back in the house to search with the bob tailing tidbit on my mind. I noticed a device in the generic prints called a tractor protection valve. I started googling for tractor protection valves under the names (Bendix, Wabco, Haldex etc.etc.) I found it under the name Haldex Two Line Tractor Protection Valve. Long story short the valve knows which emergency brakes you have released so that it knows if you are bobtailing or not. There was no mention about two way check valves though until I clicked on the more information tab and there it was. It has both of the two way check valves built into it. 150.00 dollars later it's good to go. They actually make a kit for it that cost about 25 bucks but I couldn't find any on line that weren't two weeks out so I just bought the whole valve.

HALDEX TWO-LINE TRACTOR PROTECTION VALVE KN34130

Valve Repair Kit RRN 31BC