pair of stainless steel doors that were tested on car 3119, ventilation louvres that were inserted into the side doors on car 3138, and three cross seats that were extended to permit seating by three people on car 3189. These were done during the 1970s. The R10 was the last B-Division car to have seats that had thick strand woven cloths covering the entire seat. History Pre-introduction In 1947, following an accident in 1946, R7A car 1575 was rebuilt from its original appearance by ACF and became the prototype for the R10. The car was designed to test new interior and cosmetic features. After it was rebuilt, 1575 re-entered service on June 30, 1947; however, while it cosmetically resembled an R10, mechanically and electrically, it was still an R7A and could only operate with other pre-war IND Arnines. Delivery and revenue service The R10s first ran in service on the route on November 20, 1948. They were initially the mainstay, and were exclusively assigned to this train, where they remained for almost 30 years, and became synonymous with that route for more than 20 years. During these early years, they made occasional appearances on the service (especially on weekends) and the rush hour service. Thirty cars #s 3320–3349 were transferred to the BMT Eastern Division in 1954, primarily used on Broadway–Jamaica service to help familiarize crews with SMEE equipment in anticipation of the arrival of the R16 cars, whereupon they were returned to normal IND service. Then, some R10s were finally displaced from the beginning in 1969, when brand new R42 cars, R44 cars, and displaced R40 cars were transferred from Jamaica Yard beginning on September 13, 1977 (which was, in turn, receiving brand new R46s were directly assigned to the (so that the train could be equipped with some air-conditioned cars). Many of these displaced R10s were then often used on the and later, the rush hours-only (now the and ). During 1978–1979, 2950–2999 were also transferred to Jamaica Yard for use on the (now the Brooklyn/Queens Crosstown Local). Ultimately, the fleet was essentially assigned to the and service; however, during the R46 truck crisis, they needed to be placed back into regular service as its R44s were moved to Jamaica Yard for service on the , , , and . Many R10s were used for a few weeks on the , then for a slightly longer period on