So I've just finished dropping in the engine/tranny and I just realized I'm missing this metal hose which has a bracket connected to the driver side upper bell housing bolt. I can't find it in my garage so perhaps the transmission shop I got the tranny rebuilt at forgot to put it back but it's been months since that happened so I doubt they still have it. Here's a photo from a random youtube video for visual reference. It's that metal line that runs along the top of the transmission. What is this part? I can't seem to find it in the manual on charm.li either.

 

I believe it's a vent pipe going up toward the firewall.
Mine has this and a short, metal drain/overflow tube pointing down (which would not be visible in the photo).
The dipstick is on the passenger's side.

 

Is it all one piece? Thinking of just routing a rubber house with some duck tape in roughly the same shape as the original, or just routing straight through to the engine bay somewhere I can secure it better.

 

As best as I can see on mine, it's at least 2 pieces.
The short, downward pointing metal pipe is, at ~3/8", much smaller than the upwards (vent?) pipe.
I believe correctly fitted rubber hose could work.