Note: You do come across anniversary events during Career, but it's possible to skip them. You can do them as a separate game mode however:
From the main WRC menu, go to Anniversary Events and pick the first one - 1973.
It's one special stage in the Renault Alpine, and you have quite a large margin for error to beat the given time.
With no assists and my first attempt, with no prior knowledge of the special stage or car, I beat the target time by a full 20 seconds - and I fell off a cliff once and had to be reset.
At the end of the race, your achievement will unlock.