All Door Box Car
Box Car -40ft. 5486-series
Box Car -40ft Double Door Wood
Box Car -41' Hi-Cube
Box Car -40ft. 5241-series
Box Car -40ft. 12000-series
Box Car -40ft Metal 5238
Box Car -40ft PS-1
Box Car -40ft Rivarossi 5279
Box Car -40ft Wood-Sheathed
Box Car -50ft Combination Door
Box Car -50ft Double-Plug Door
Box Car -50ft Plug Door
Box Car -60ft Single Door
Box Car -Old Time
Bulkhead Flat Car
Caboose -Bay Window
Caboose -Extended Vision -Roco 5485
Caboose -Extended Vision -12000
Caboose -Old Time
Caboose -Old Time Drover's
Caboose -Standard Cupola
Caboose -Streamline Cupola
Calcium Carbide Car
Cattle Car -40ft. -1st Version
Cattle Car -40ft. -2nd Version Roco
Cattle Car -40ft. -3rd Version Hong Kong/Taiwan
Center Flow Hopper
Coil Car
Container Carrier
Covered Hopper -47ft.
Crane Car
Flat Car
Flat Car -Old Time
Flat Car with 2 Autos
Flat Car with Bridge Load
Flat Car with Boat Props
Flat Car with Cable Reels -Lima
Flat Car with Cable Reels
Flat Cars with Trailers
Flat Cars with Containers
Flat Cars -Specialty
Flat Car w/Truck Load
Flat Car -16 Wheel with Load
Flexi-Flow Hopper
Gondola -Old Time
Gondola -40ft
Gondola w/Load -40ft.
Gondola -50ft. Outside Braced
Gondola -50ft.
Gondola 50-foot -Hong Kong
Helium Carrier
Hopper Car -40ft Open
Hopper -50ft. Ribbed Side
Horse Car -Old Time
Log Car
Palace Stock Car
Pulpwood Car
Ore Car
Reefer -40ft Private Owner
Reefer -41ft
Reefer -50ft. Outside Braced
Reefer -50ft. Smooth Side
Reefer -50ft Thermo King
Stock Car -50ft.
Stock Car -Old Time
Tank Car -50ft. In-Transit Heated
Tank Car -Chemcial Tank 40ft.
Tank Car -Single Dome 5276
Tank Car -40ft.
Tank Car -40ft Three-Dome
Tank Car -40ft Six-Dome
Tank Car -62ft. Single-Dome
Tank Car -Old Time 6255
Tank Car -Old Time
Track Cleaning Car
Vinegar Car
Watermelon Car
Wreck Crane with Work Car
Wrecking Crane
Track Maintenance Car
Old Time Cars
U.S. Army Trains
Jumpin' GI Jeep
Action Cars
Operating Cars

AHM Outside Braced Gondola

50-foot Outside Braced Gondola
Milwaukee Road
No. 5299E -1971 Release

AHM Outside Braced Gondola

AHM Outside Braced Gondola

50-foot Outside Braced Gondola
Ohio Seamless Tube
No. 5299B -1971 Release

50' Outside Braced Gondola
Pittsburgh & Lake Erie
No. 5299-D -1971 Release

50' Outside Braced Gondola
Rock Island
No. 5299-F -1971 Release

AHM Outside Braced Gondola

50-foot Outside Braced Gondola
Santa Fe
No. 5299C -1971 Release

The AHM HO-Scale 50' Outside Braced Gondola arrives in the product line in early 1971.  The model is likely designed or inspired by the war-emergency practice of utilizing wood slats in place of steel during the WWII period.  Many examples of these war-emergency cars would be rebuilt with steel panels following the war, thus dropping the interesting makeshift design appearance of steel bracing holding wood panels.
Original roadnames included Ohio Seamless Tube; Santa Fe; Milwaukee Road; P≤ and Rock Island.  The early AHM ads for the model displayed a C&EI example, which was not among the initial roadnames.  The model retailed for $2.49 back in 1971. 
The model has also found in Model Power's product line and was also present in the IHC-Hobby line. 
My example is a Roco Austria import by AHM.  I believe later examples exist produced by Mehano in Yugoslavia.

If you're looking to make the AHM offering a prototypical piece of rolling stock, it is possible. Check out Rail Model Journal's October 1994 article, Kit Converstion: 50-foot EJ&E Gondola from AHM's HO Scale Model available online at theTrainLife website. John Nehrich's article includes some prototypical analysis of the AHM tooling, inlcuding mention that the car's 50-foot length is too short for accuracy.

AHM Outside
                           Braced Gondola

AHM Outside Braced

AHM Outside Braced Gondola

AHM Outside
                                             Braced Gondola