There was also 98 - St. Marks/Hockaday from Dallas. Dissolved sometime around 2001 due to major sponsorship issues. Their last year was the year before my freshman year.
The schools split into two teams and both moved to BEST. I'd kill to get an FRC team restarted there, but thats a challenge now living on the other side of the country.
And are you sure 55 is Austin Acad? That is a middle school. (I remember them from BEST)