The R10 was the first series of post-war New York City Subway car class built by the American Car and Foundry Company in 1948 and 1949. These cars were nicknamed Thunderbirds by their operating personnel and rail fans because of the cars' high speeds. The R10s were mainly assigned to the IND Eighth Avenue Line's A train from 1948 thru early 1978, when they were replaced by the slant-ended R40 cars transferred from Jamaica Yard's E, F, and N lines which in turn were receiving brand new R46's during this period. They were reassigned from the A line to the rush hours only CC (now C) line, with some still remaining on the B line effective April 1978 due to aging. Some were also transferred to Jamaica Yard for use on the GG line, and help fill a car shortage created by the R46 truck problems wh