Here's the info: I am a little biased because I work on the train

But it is really a great tour if you love trains or Disney History
A great way to learn about the Walt Disney World Railroad is to take the Magic Behind the Steam Trains tour. If you have any interest at all in steam railroads, this tour has something for you, whether you know a lot about them or nothing at all. The tour also has a lot to offer for those with an interest in Disney history in general. Much information is presented on Walt's interest in railroads, including his Carolwood Pacific Railroad that ran around his home. The particular history of the engines of the Walt Disney World Railroad and how Disney acquired them is also presented.
The highlight of the tour is a visit to the roundhouse where the trains are kept and maintained. Guests are even allowed to climb in the cab of one of the engines, giving them an upclose look at things most guests do not see. The procedures for operating the Walt Disney World Railroad are demonstrated and explained, showing everyone that the Railroad is much more than just a simple amusement park ride
Location and Time:Mondays, Tuesdays, Thursdays & Saturdays at 7:30am. Guests should arrive at least 15 minutes prior to start time. The group will meet at the Guest Relations Window, outside the Magic Kingdom Main Entrance.
Duration:3 hours
Cost:$40.00 per person (Theme park admission is required.)
Restrictions:Guests must be at least 10 years old to attend this program.
Discounts:
DVC Members: 15%
Packages:
Silver, Gold, and Platinum Plans
For more information and reservations call (407) WDW-TOUR (407) 939-8687.