It doesn't look like a Bendix. It could be a Sloan. Where do the lines go. It may be an old tractor protection valve. If it has a tractor protection switch on the dash, it was once tractor equipped. The normal is for driving. Emergency kills the air supply to the trailer. If it is now a bobtail, you don't need any of this. What leaks when you have it in the normal switch. Is it the valve on the dash, or is it the valve in the picture? If it is the valve in the picture, you don't need any of this if you don't pull a trailer and it is best to plug it at wherever it gets its air.
