I saw the full portion of the episode involving the train and the first exterior shot shows two SP SDP-45s pulling pre-Superliner steam heated heritage equipment. Another scene later shows the train being pulled by a single Amtrak SDP-40F 500-class loco. Another scene has the camera close up alongside the train and that was filmed at LAUPT. The train was called the "Sunset Express" and Jim Rockford's dad Rocky reads a schedule, noting that the train will be making a stop in Thousand Oaks. Later on, James Garner and Ned Beatty are supposedly walking along the track where the train ran, looking for a piece of luggage that had been tossed off the train. They're walking along a very light density branch line and I wasn't able to figure out where it was filmed. Maybe the Santa Paula branch?

Here's the episode. Fast forward to about the 36th minute.

[dai.ly]