The AAR standard design for 40-foot steel boxcars (adopted in 1932, revised in 1937 and again in 1942) was easily adapted for use as a double-door auto car. Such cars were placed in service by a number of railroads during the late 1930's and 1940's A representative auto car version of the AAR steel boxcar was the Union Pacific's A-50-16 class, 500 of which were built in the UP Omaha shops in 1940. These cars, numbered 474000-474499, were virtually carbon copies of the B-50-27 class AAR design boxcars being built by Union Pacific at the same time. The only differences were their twelve-foot Youngstown corrugated double doors and an additional six inches of interior height. A photo of UP 474000 when new in August of 1940 appeared in the 1943 and 1946 editions of the CAR BUILDERS CYCLOPEDIA and is reprinted in Newton Gregg's TRAIN SHED CYCLOPEDIA No. 77.
Equipped when new with Evans type E auto racks, the A-50-16's were used primarily for shipment of new motor vehicles until the mid-1950's. In 1955, the racks were removed and they were renumbered 175000-175499 and assigned to general merchandise service. In this role most of the class survived into the 1960's and some were still active until the early 1970's.
Since these UP auto cars closely resemble AAR boxcars, they can be modeled in HO scale by converting Athearn's 40-foot steel boxcar kit. Auxiliary doors are made from an extra pair of Athearn boxcar doors by removing the placard boards and relocating the operating lever and grab handle. The small destination card boards should also be removed from all four doors, as these were located on the sills on all UP steel box- and auto cars.
I improved the appearance of the doors by cutting off the bulky door slides at the bottom, adding additional panels at the top, narrowing the vertical flanges on the sides, and cutting down the oversize upper and lower door tracks. Then, after cementing the doors in place, I made and installed new auxiliary door tracks using styrene strips. I also added scale size door guides and latch details made from styrene and wire. Styrene strip stock was used to form the side sill reinforcements below the door openings and the destination card boards on the sills. Other improvements included filling the holes in the roof with styrene plugs, installing wood running boards in place of the kit's steel-grid type, and removing the top ribs from each end to represent the prototype's 5-4 end configuration. Underneath the car I installed storage tubes for the auto rack tie-down chains. These were made from 1/16" Plastruct tubing. I replaced Athearn's air brake equipment with a Cal Scale No. 283 AB brake set, and added brake rigging. I then completed the car by fitting the Cal Scale brake wheel, making uncoupling levers from .015" brass wire and Detail Associates No. 2206 eye bolts, and fitting new sill steps made from flat wire staples.
When new, the A-50-16's were boxcar red with black underframes and trucks. All lettering was white except for the "Streamliners" slogan on the right side of the car and the "Serves All The West" slogan on the left. These were yellow. I lettered my model using a Champ HN-39 roadname set, slogans from a Champ HB-60 boxcar set, and data from Micro-Scale sheet No. 87-02. Repainted cars were entirely boxcar red, including trucks and underframes, and cars repainted after mid-1947 had all lettering in yellow. Later, many A-50-16's were repainted in the "Be Specific" scheme of the 1950's, and some probably finished their careers in one of the Union Pacific's colorful 1960's-vintage paint jobs.