This very nice 3-rail AC HO gauge locomotive by Marklin is 3546 a DB V36 diesel locomotive in black livery. It has running number V36 123. 

The WR 360 C 14 Wehrmacht diesel locomotives were created in the late 1930s as shunting locomotives for the German Wehrmacht . The type designation refers to a Wehrmacht locomotive for standard gauge with 360 hp, axle arrangement C (three coupled drive axles ) and an axle load of around 14 tons.

The locomotives were built for Wehrmacht locations at risk of explosion ( refineries , tank farms and ammunition depots ), but also for ports , airfields and the like, where steam locomotives would have given away the locations with their clouds of steam and smoke. An example of this was the army research institute in Peenemünde 

261 locomotives of this type were built. The wartime diesel locomotives were used throughout Europe during the Second World War and - especially in the case of the four-axle variant - also in North Africa. After the war, both the Deutsche Bundesbahn (DB) and the Deutsche Reichsbahn (DR) classified diesel locomotives of this type as the V 36 series.

Between 1955 and 1959, seven locomotives received electro-pneumatic controls that could be operated by just one man. For these operations, some V 36s were subjected to a major modification: Because driving with the (quite high) front end was always somewhat problematic and prevented one-man operation, a pulpit was placed on the driver's cab . The locomotive driver then stood at the driver's desk in much the same way as the captain of a ship would stand on his bridge.

After the delivery of more powerful locomotives, especially the V 60 series , the V 36s moved to light shunting service, work trains and workshop service. In the 1970s they were decommissioned from the Deutsche Bundesbahn and in the 1980s from the Deutsche Reichsbahn.

A number remain in preservation

The loco is in good condition as you can see in the pictures, We are unable to test it as we do not have a three rail AC test rig or track, so we have not tested it but can see no reason why it would not run. It is sold in untested condition, this means that it may not run, and as such it is not being sold in running condition. However a complete external visual inspection has shown no reason why this loco would not run and the overall condition is very good though it is missing one buffer. The box is in good if slightly shelf worn condition, the inner liner has yellowed and is going brittle as is normal for Marklin locos of this era. 

Overall this is a really nice scale locomotive and would look fantastic on a layout.

Do please have a look at my other listings, I typically have various HO and OO locos on offer as well as an extensive range of imported N gauge locos and other items. 

Note: I do recommend all locos are cleaned & serviced, as they have some age to them even if the quality looks at the highest level (fairly standard advice for all locos!).