A904LA transmission issue

Hey guys!

Purchased this cuda a couple weeks ago and have posted a handful of questions since then because this is my first classic I have owned (worked on a mustang with my dad a while back) so please bare with me haha. I’m focusing on safety first as far as making her driveable (which technically it is). I was underneath after cleaning off some sludge searching for a few leaks (so far engine oil pan & drain, intake manifold, and valve covers) when I noticed this on the transmission. Searched the service manual and I couldn’t find exactly what this line is but I want to make sure I get it fixed asap. I know it’s inboard of the throttle linkage and I found the diagram for the throttle linkage that shows this line but it doesn't give it a description. You guys have been amazing help thus far and its very much appreciated thanks!

IMG_B34468EDA471-1.jpeg