2010 T660 new style leveling valve.

Hi folks,
I was working on a T660 dump today, and I had the displeasure of having to replace the leveling valve for the front drive. It's on the passenger side frame rail right above the front axle. It was leaking right out the side. It was a hassle. It still had the original black paint on it, so I'm thinking it was original. Anyway, it was a Haldex and MHC Denver gave me a Barksdale type to replace it. It took me awhile to figure it out. There's only a couple lines, but it took a little swapping around. I finally got it, but there was one line that had to be left off. The 3/8 lines were for the supply and the bags, but the smaller (maybe 1/4") on top of the Haldex had to be left off the Barksdale. I tried to trace it, but I lost it in a bundle and couldn't see where it came out. Does anyone know what that smaller line was for? The one on top of the original Haldex valve? I attached a pic. You can see the lower 3/8 line to the lower left, and kinda see the upper 3/8 line behind that other hose. The one on top of the valve is the one in question. I just couldn't find where it went.

 

I even called them and asked about it. They said that's the superceded part. Then I talked to their service guy, and he said it's probably a vent. I told him you guys sold me this valve and I didn't call him looking for a "probably", I called looking for a real answer. He said "yeah sorry".