M35A3 question: What's this thing? Pictures...

I'm continuing to go over my truck and trying to learn what each item is and what it does. There is a "thing" on the left side (drivers side) of the engine that looks like a filter could spin on to it but there isn't one. There is also a hose that exits the same "thing", bends down towards the ground and that is angle cut on the botton and open. It's located roughly in the area where the oil dipstick and filler tube are at, to the rear of the compressor.

Is there supposed to be a filter on it? Or leave it as-is?

I tried looking through the TM's but I don't know what its called....

Leave it as is , it doesn't do anything . There are several threads on it.
M35a3 3116 missing engine part ?

coolant filter maby?

This is only used on teh Civvy CAT 3116 engine.