Yeah, Laverne and Shirley went up to the mid-to-late '60s. They'd reveal what year they were in at the beginning of the opening credits.
I was always told that Happy Days was supposed to have begun in 1953 (although Richie did tell a date that he had heard the Giants were going to move to San Francisco- which they did after the 1957 season- in an early "Rock Around the Clock" episode). There is an episode late in Happy Days' run, after Richie and Ralph left, that had Joanie hold up a sign that dated the episode in 1962.
Some instances in the show that relate to earlier topics about sex-
1. Remember when Laverne and Shirley first debuted? How Shirley accidentally knocked Richie out, and then with Rich on the floor suggestively told him she kiss his "boo-boo" right as the family walked through the door?
I have a friend who INSISTS this was to initially set Laverne and Shirley as promiscous girls that Fonzie thought he and Rich could score with- while in later L & S episodes they were made out to be virgins who never "foe-dee-oh-doed."
2 Or when a young woman came into Arnolds or somewhere with a baby in her arms looking for Fonzie- upon which when she saw him he introduced himself as Potsie?
3 Early in the show when Rich has the house to himself, is going to have an all night poker game with Potsie and his pals, but then some college age women break down and they cancel the game, hoping they can score with the women, only to realize the young ladies think of Rich and Potsie as kids and not anyone to be romantic with?
4 What about when Fonzie lends Rich his apartment for a date so he doesn't have to admit he lives with his parents, and Rich loses something in Fonzie's sleeper sofa?
"Where is it?"
"It's in the bed, Fonz!"
"That's my boy!"
5 Three words- Tunisian Camel Jockeys.