The tube between the carb and air cleaner was wired up to the manifold on my 1650 tractor. I think it should be bolted to one of the studs that retains the manifold, but the hole is broken out. I can repair that easy enough. However, there is also a brass union on the opposite side of the tube and no lines that connect to it. This has me wondering if I have a correct air cleaner assembly for my tractor or if someone switched it out. 

I'm sure I can make it work, but I was just wondering what is correct.

I've attached a picture of the tube.