Couple of questions on my K1500

[Red88]

First of all let me thank all of you for the great information on this board! I bought an 88 K1500 for $1100 back in June. While it didn't smoke or knock it was roaring, idled crappy, hesitated, was hard to shift and I hadn't worked on a automobile for about 25 years. With your help all those problems have been solved with some testing, parts, and dirty work! Much more to do and looking forward to finding the answers that help here brings.

I've noticed what appears to be filler or vent tubing (see attached image) in two places; one to the right of the radiator leading down toward transfer case and the other behind the distributor in a similar place to where auto trans dipstick would be (it's a manual MG5 Getrag). What are they for?

I drained the tranny and refilled with Penzoil synchromesh tranny fluid (which showed the correct GM spec). I thought it was supposed to hold 2+ quarts but, after draining thoroughly it would only hold about 1-1/2 quarts so I'm kinda concerned that it is short of fluid. Any thoughts?