This car is part of the collection at the Baltimore and Ohio Railroad Museum in Baltimore, Maryland. It is one of my favorite prototypes and this car has been nicely restored and placed on display outside the museum roundhouse.

The M-27 was an interesting car series. B&O built 2,000 cars in 1926 for automobile service in both 1-1/2 and double door configurations. The cars were built with a 9-foot interior height. During this time freight car design was evolving rapidly, and within a few years these cars were already obsolete for carrying automobiles. The introduction of the Evans auto loader, which required a minimum 10-foot interior height car–allowing automobiles to be stacked inside box cars–was unable to be fitted in the as-built M-27. PRR Also had this problem with its vast X28-series cars.

In response, in 1934, B&O rebuilt 501 M-27s with a Mansard-style roof that allowed a loader to be fitted inside. Then, around 1940, B&O converted the entire M-27 series–including the rebuilt cars with Mansard-style roofs–back into general service box cars. Ultimately there were six variants of the M-27, with over 1,900 of them still in revenue service in 1950. We are fortunate that this car, an M-27F, still exists.

Sunshine Models offered HO scale resin models of all six versions through 2012. They can occasionally be found on eBay or at train shows. It is possible to model the car in HO (Red Caboose) or O (Middle Division) using the 1924 ARA car/PRR X29 as a starting point but the carbody is a few inches too short (8′ 7″ IH vs 9′ 0″ IH on the M-27) which will force the modeler to make some compromises.

Above.  For reference, this is a PRR X29 at the Strasburg Museum in Pennsylvania.  It is about six inches shorter interior height, and has many other differences.

I hope you all find this post helpful.