system (220/380V, 50 Hz) and were the first Mark 3's to be fitted with automatic swing-plug doors. There were also some different internal layouts more specifically suited to Irish traffic. Twenty-four coaches were built for push-pull operation on the suburban rail service including five built to Control Cars (6101–05, 6301–19). Originally used in conjunction with the 121 Class locomotives they were last used with 201 Class locomotives. There were a number of differences between the Irish push-pull Mark 3's and the standard Mark 3's. An underfloor generator, mounted in the Control Car, provided electrical power to the coaches; unlike on the standard Mark 3's, which used a special generator van. This single generator was not as powerful as the two used in the Mark 3 generator vans and was the main reason the sets were limited to 6 cars. Irish Mark 3 push-pull based rolling stock did not have air conditioning and had opening windows instead. There was also a 70 mph speed restriction imposed on the train due to the fact that three of the Control Cars were fitted with LHB bogies from an 8100 Class DART and were air-braked. In 2004, a 1979 vintage British Rail Mark 3 TRFK (Trailer Restaurant First Kitchen) coach was converted by Interfleet into a modern Snack Car for use on a Push-pull set. This set was usually used on the Waterford route. The Mark 3A "Cú Na Mara" set, now withdrawn, operated exclusively on the Dublin to Galway route, and was originally the BREL International Train, a showcase project designed to secure overseas orders. The set travelled to a German rail exhibition in 1988, but returned without any new orders and languished for some years before being sold on through Vic Berry. CIÉ converted the many different interior layouts to their own standard design (6201–08 ex 99521–22/24–29, Restaurant Buffet 6401 ex 99523), fitted their own Mark 3 type powered door and re-bogied with ABB bogies. Although also re-wired for Push-Pull operation the fact that an additional coach wasn't converted to a Driving Brake Standard (planned 6501 ex 99520) prevented the set from ever running with this configuration. This set marked the end of coach building in Inchicore. The plug door design found on the CIÉ Mark 3 coaches was later used on the British Rail Class 442 long-distance commuter train. In 2008, IÉ announced plans to sell off the Mark 3 fleet.