That's particularly egregious but alot of 70s and 80s stuff that would get a PG-13 now was rated G, including True Grit and Oliver! The Golden Voyage of Sinbad was also G, but that would probably still get away with a PG now.
On the other hand, some stuff from the 70s and 80s that was supposed to get rated X for violence would only be R now.
Dawn of the Dead and Day of the Dead were released without ratings because although releasing a movie without a rating was normally considered bad business an X for something that wasn't porn was considered worse.
Assault on Precinct 13 was X until they cut out the ice cream scene for the censors, and the put it back in before sending it to be printed. De Palma did the same thing with the scene in Scarface where the clown gets killed in the nightclub (I think he did that less because he cared about that scene and more out of spite).
Last House on the Left was supposed to be X but Craven stole a "Rated R" label and stuck it on the copy he sent to the distributor, or something like that. But maybe that would get an NC-17 now?