Ace's TARDIS was given to Ace when she joined the Celestial Intervention Agency for her to undertake missions.
It had a working Chameleon circuit, which Ace despised when she often had to find it when running away from angry populations she had to encounter on her missions. This TARDIS was able to be entered by other Time Lords, such as when Ace found Rexx. Like the Doctor's TARDIS, it contained a Cloister Bell, which warned Ace when the Earth was about to be sucked into a black hole.
It was able to connect to the Hand of Omega, which Rexx used to his advantage. Rexx used this TARDIS to open a gateway to Omega's universe in order to free him, travelling through the Black hole. Later Omega stole this TARDIS to escape into the main universe, since it had immediate access to Gallifrey due to Ace‘s privileges of being a CIA agent and a friend of President Romana. (AUDIO: Intervention Earth)
When the timelines were rewritten by Irving Braxiatel to stop Omega's release, Ace piloted her TARDIS to Outpost Delta, on a mission by Coordinator Romana II. (AUDIO: Enemy Lines)