http://www.trainsarefun.com/lirr/Freight%20after%201966/Freight%20After%201966.htm The AAR began a program of consolidated Stencils in 1972 which applied to new or rebuilt freight cars only and only had air brake info. Application to existing cars was not mandatory. The FRA (Federal Railroad Administration) created in 1966 issued in July, 1974 a mandate for all freight cars to begin having the new consolidated stencils applied. These stencils are applied on the lower right end when facing the car side.
Defined by the AAR, the large single panel COTS were optional and applied to new and rebuilt cars from 1972 to July 1, 1974. On that date the two part COTS, with the lub info, became mandatory with a deadline of 1979 for application to all cars. Since 1982, subdivided into three or four parts, however shortly thereafter, this was revised to three panels. References 12/1978 RMC, and 1/1982 RMC. Info: Jim Eager