The MP 73 is a rubber tired variant of electric multiple units used on Paris's Métro system. The cars were delivered in 1974, when the RATP decided to convert Line 6 to rubber tyred pneumatic operation. The existing stock on Line 6 needed replacing at this time, and the line was converted to rubber tyred operation due to the lengthy open air viaduct sections of track, which generated much noise and vibration with older steel-wheeled rolling stock. The body design was based on the successful MF 67 stock. A total of 252 cars were built, six of which have subsequently been scrapped, leaving 246 cars. They were refurbished in 2000. Trains are formed into 5-car sets, and they continue to serve on Line 6.