Just another use for those surplus Troop Sleepers. The Allied Full Cushion trucks have been replaced with what appears to be a Commonweath or a ACF high speed truck. The shot was taken during the fall of '74 at the West Shops, Springfield. For the modeler, Walthers has a Rock Island car that would require the removal of the CRIP lettering, and the application of the new Frisco lettering. Swap out the trucks, and one would have a nice Frisco car with a couple of hours work. http://www.walthers.com/exec/productinfo/932-4164
Many railroads replaced the old two axle scale test car with a two-truck, four axle car in order to allow a train conveying the car to move it in any position in a train and without speed restrictions. I don't know if it was so in this case. I do know that two-truck, four axle scale cars were also used for testing retarder systems in hump yards, where the two-axle cars would not be for that purpose.