I'll never forget the sound of this trio of V20 EMDs. We were on a roadtrip with my wife, having flown from Helsinki, Finland to SFO couple weeks earlier.
One of my choices for the destinations to see was Mullan Tunnel, hopefully spotting an MRL train at a classic location. We had driven from Kalispell to Blossburg early in the day, we waited for a couple of hours having no idea if a train was coming or not. Just about to leave, I noticed headlights approaching the far end of the tunnel. When the headlights neared the tunnel portal, I realized how lucky I was - it was to be a trio of EMD SD45-2XRs. For me this was the first - and possible the last - time hearing these monsters. Oh my what a rumble the 645s produced! I've seen and heard my fair share of modern EMDs and GEs on my other USA roadtrips, but this was something I really wanted to catch before it was too late.
My wife? She was sleeping in our rental car, knowing nothing about the goosebumps I got seeing these beasts.
The EMD SD (special duty) series are a strong and reliable kind of locomotive which still serve America's rails today. They have proved themselves reliable by clocking in several million miles of freight service over several decades.