I thought I knew but now I'm not entirely sure. I assumed it was the hose that terminates near the transmission crossmember on the driver's side. The picture below is of the location on my van.

I looked it up and some people say it's there and others talk about a hose coming up and mounting near the bell housing with a plastic nipple. I also have a hose just like that in the other picture under my dog house.



The streaking on your dipstick might be a lot of metal paste in the pan that the dipstick is poking into and pulling up with it. I saw in your other thread where you're planning to drop the pan. You might find a lot of metal paste in there.