what year did shows stop making these? I know it was sometime in the early 70s. And when did they stop showing/mentioning the sponsor/sponsors in the opening/closing?

i know the lawerence welk show was doing it as late as 1980 and hee haw did at least one with grandpa jones for fibercon in the late 80s

Today I've still heard occasionally that a program is sponsored by...

As for cast commercials, I've seen those for Kellogg's Corn Flakes by The Partridge Family, but I've never seen any Brady Bunch cast commercials and don't think any exist. (Those would be something to see today!)