Check Valve for 1999 FLC112

Howdy guys..... I'm certain this is a dumb question, but please bear with me. This is my first Class 8 truck and and wrenching on air brakes is a new endeavor. I believe what I am pointing to in the picture is a Single Check Valve. I also believe these 2 check valves are connected to the Tractor Protection Valve. This is where my leak is occurring and I need to replace them. Only trouble is, after searching through what seems like a million sites, I can find no check valves that look like this. It's on a 99 Freightliner Century. Any help you could lend would be great..... Thank you

 

Thank you sir!..... easy as pie when you know the right name for it. Much obliged to you.

 

Question 2.....seems as if there is also a leak at the switch....perhaps a bad manifold or valve? Short video link above
Thanks again for any help

 

Thanks again QT..... gonna owe you a keg by the time this over.... I truly appreciate it.

 

Just wanted to circle back around and say thanks again for the help. Went down to pick the truck up on Saturday, armed with the advice from @QUALITYTRUCK and got it back on the road and home. Since then I have found a leak in one of the lines coming from the governor and a leak at the parking brake valve on the dash. Fixed the governor line, but need to order a new parking brake valve still..... Other than that, a broken city horn, broken cruise control, and a drivers window that doesn't work, it's almost fixed.....lol