I think you are getting her 70s film career mistaken with someone else’s. Grease was fantastic but that was her only success in film.
The only other movie she made in the 70s was “Toomorrow” and it was shown at one theater for one week.
Even if you go through 1990 she only made 3 other movies, “Xanadu”, “Two of a Kind” and “A Mom for Christmas” (a television film). None did well.
And she was not in Saturday Night Fever.
I guess you’re right. I thought she was in Saturday Night Fever. Probably because Travolta was also in it.