I'm so glad there are so many of us "oleo/material" gals here, and yes, I remember the sweet milk, too, as opposed to skim milk, buttermilk, sour milk and cream. There was no 1%, 2%, Silk or Soy. (There were soy milk formulas for babies who were allergic to cow's milk.) I have an old Betty Crocker cookbook that calls for sour milk in lots of chocolate cake recipes. I seldom "made" sour milk with vinegar - milk would get sour faster in those days, I think. It really didn't take too long, either. It always gave me a good excuse to make good chocolate cake.
Remember the milk man and the milk box by your front door? Ours also delivered eggs, butter, cottage cheese, sour cream, etc. - anything dairy. If I needed something more than the regular milk order, I would leave him a note telling him what to deliver the next time - I had to plan ahead and be organized!
Boy, we've really gotten away from "Squash Casserole", haven't we?