Being a huge SW fan I remember seeing the original in the theater as a little kid and I was hooked! In the original trilogy (movies) the word "Sith" was never mentioned. I also was a big fan of That 70's Show and I know Eric Foreman was also a he SW fan as well. There was an episode where he is showing Red his SW figures and he describes Darth Vader as a Sith. Was that mentioned in the novelizations of the original movie? I didn't hear Sith until Episode I.
Thanks and may the Force be with you.
Yes, in the Novelization for Star Wars it labels Vader as Dark Lord of the Sith.