Which version of the Nutcracker did Gelsey Kirkland dance? New York City Ballet's or American Ballet Theatre's?
Both, actually! Ms. Kirkland began her career at City Ballet where she danced the Balanchine version. She later joined ABT however, and famously danced the role of Clara in the 1977 televised version of Mikhail Baryshnikov's Nutcracker. That's probably the performance you're thinking of.
Do other ballet companies ever change Nutcrackers?
It's actually pretty common for companies to make the switch every so often in order to keep things fresh for the audience and the dancers alike. Ballet companies that have unveiled a new Nutcracker in the past ten years include: San Francisco Ballet, Washington (DC) Ballet, Boston Ballet, Cincinnati Ballet, Ballet Arizona, Pittsburgh Ballet Theatre, and Nashville Ballet (which debuts its new production this December).