This very nice 3-rail AC HO gauge locomotive by Marklin is 3665 a DB BR260 diesel loco in red livery. It has running number 260 787-7.

The V60 class of diesel shunters was introduced by DB in 1958 to address a need for small shunting locos. Several of the locomotives were given a stronger frame and had a higher adhesive weight of 53 tonnes (52 long tons; 58 short tons) instead of 48.3–49.5 tonnes (47.5–48.7 long tons; 53.2–54.6 short tons). In addition these engines could carry up to an extra 6 tonnes (5.9 long tons; 6.6 short tons) of ballast for heavy duties, however they continued to be classed as V 60s. A total of 942 locomotives of this class were built. In 1968 the V 60s, like all other DB locomotives were given computer readable numbers. At this point the class was divided into Classes 260 (light variant) and 261 (heavy variant). 

They were also used in Norway, Greece, Turkey, Belgium and Croatia. The engines were not just used for shunting, but also for light goods and passenger train services. They were even employed hauling departmental trains. 

Of the 942 locomotives originally supplied to the DB, many are still active - so this loco would look good on a period or modern layout. 

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. The box is in good if slightly shelf worn condition. 

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!)..