the british rail class 304 is a type of electric multiple unit. they were built for suburban use on the first phases of the west coast main line electrification between crewe and manchester/liverpool/rugby. they were at first classed as am4 units and later became class 304 under the tops numbering system. they could be found in operation over most of the southern west coast main line. the units conformed to the 1959-design for alternating current (ac) electrical multiple units, and were externally very similar to the class 305, class 308 and the 1,200 v direct current (dc) class class 504 units. no units survived preservation, and all units were eventually scrapped.