You are correct, it was a predecessor, called "Mine Train through Nature's Wonderland" It was situated on the site now occupied by Big Thunder, but was a much gentler ride, being a train ride rather than a roller coaster.

There are still traces of the old ride, including several buildings from the town of Rainbow Ridge, which was where the Mine Train ride loaded.

Big Thunder Mountain Railroad is a mine train style coaster, powered in the normal lift hill and gravity manner, though it does have a shell resembling a locomotive on the front of the coaster trains.

More info on the Mine Train:

http://www.yesterland.com/minetrain.html

As expected more than one train set.
Photo of engine with bike, 00174 and ??
http://www.flickr.com/photos/63781710@N05/7435179090/
http://www.pbase.com/image/93985246
Peek into cab but no bike, 02954 and 04982
http://www.flickr.com/photos/8348059@N0 ... otostream/
http://www.flickr.com/photos/8348059@N02/1992941818/

By the way one of the reasons Disney has cubic yards of money is limiting operating costs. I’m guessing 99 percent of the folks buying a ticket on this thing don’t know or care they cost cubic feet of money per month less to operate than steam.

I would say that's true in this case, since the ride isn't about riding on an authentic steam train, it's about getting to and from part of the park, and seeing animals. Also, you're at Disneyland, it's an amusement park, not a museum, and full of simulation and replicas. I hear they don't use real ghost in the Haunted Mansion either. Heck, when you ride the Jungle Cruise, the boat isn't steam and the animals are fake too!

Generally speaking, people do know the difference, and appreciate riding behind steam.

Early in the operation of the Mt Rainier scenic we tried running 5 trains per day (it was busy back then!) 3 steam and 2 diesels. They soon discovered that most folks preferred the steam and many would wait for the steam train rather than riding the diesel.

Obviously this will vary depending on the operation. Mt Rainier Scenic is mostly about the train itself. Yes, we have a view of Mt Rainier, but the majority of the ride is in the woods. People ride the train for the experience of a steam train ride. In other locations, they ride the train to travel to scenic areas, such as the Mt Washington Cog and the Grand Canyon Scenic.

That said, steam outlines can fool people. If it looks like a steamer and has a whistle that sounds like a steam train, many people will assume it is. Six Flags uses this to their advantage, running converted steam locos powered by a hydraulic drive in the tender.

Thanks for the link to Yesterland. I remember the first time I took my daughters to The Magic Kingdom in the early 1960s, the younger one referred to it as "Busyland". I first visited the park in 1956--one of my uncles was a construction engineer and he figured out how to keep the "Rivers of America" from losing water and turning into the "mud puddle of Anaheim". In addition to his consulting fee, he received a stack of day passes for family members. By then the park had "settled down" after some of the opening-day problems. Now I have to get down to the California Adventure and check out the Disney version of the Pacific Electric Red Cars.