Re: 1976 70hp looper weep holes
You're referring to the exhaust relief ports...those are there to relieve some of the backpressure on the underwater exhaust, to make facilitate starting and idling. Running on the muffs, you may occasionally see a fine mist come out there, but usually nothing. With the lower unit submerged, exhaust and cooling water exit there at slow engine speeds.
I don't believe that model has a "telltale" or "pee stream" or "overboard water indicator" or whatever terminology you like. Many people have successfully installed one using this excellent illustrated tutorial:
http://forums.iboats.com/showthread.php?t=222677
