After the R36 cars were delivered in 1963–1964, no more IRT cars were built for another 20 years. Several rolling stock orders were proposed for the IRT during this time. In 1966, a lightweight R39 subway car, similar to the ones used on the Market–Frankford Line in Philadelphia, was proposed for the oldest elevated IRT and BMT lines; however, this proposal failed because most of the remaining elevated lines were closed, and demolished instead. In 1973, another proposal to replace the R12 through R17 series was deferred because not enough voters approved it. Finally, in 1979, with the bus and train fleets in poor and decrepit shape, the New York City Transit Authority (NYCTA) looked into capital maintenance and bond acts to replace the oldest IRT cars (the R12s, R14s, R15s, and R17s) and to rebuild and refurbish newer (at the time) IRT cars (R21s and beyond). A bond issue for 136 new IRT cars was approved, and funds were procured for another new 1,014 IRT cars in 1981. These cars were referred to as the "R62" contract. The R62 order was originally proposed as an order of 260 cars, each of which were to be long. The selected plan called for 325 IRT cars instead.