It wasn't until 2003 that the Olympics had a formal policy for trans participants, requiring gender confirmation surgeries, including the removal of the gonads and changes to external genitalia, as well as legal recognition of their gender and two years or so of hormonal treatment.
Perhaps unsurprisingly, there were no trans Olympians. These policies were changed in 2015, to ease the legal and surgical requirements.
While the policies moved to allow transgender people to declare their gender, they did include a requirement that a transgender person have less than 10 nanomoles per liter of testosterone in their system.