EWTN has made available the audio files for previous episodes of Journey Home with Marcus Grodi.
Some recent ones:
With Fr. Erik Richsteig of Orthometer, former "cultural Mormon"
With Fr. Eric Bergman, former Episcopal priest
With Dr. Francis Beckwith, former Evangelical
Some older episodes:
With Avery Cardinal Dulles, S. J., former Presbyterian
With Fr. Richard John Neuhaus, former Lutheran minister
With Fr. Dwight Longenecker, former Evangelical and Anglican