Although the above is correct, Mr McGavin did reprise his role in this episode, at least for 2 scenes. The Season 6 DVD features 2 alternate takes for scenes shot in the episode with Darren McGavin. Scene one is the scene in the kitchen where Mulder asks if the great glories of the past were aliens and the 2nd scene was one of the last in the episode, when Mulder says goodbye to Arthur Dales. Such a shame that he was unable to complete the episode. Great actor, great performance.