For 1969, GM installed the L-72 427 solid lifter engine in both 4 speeds and autos, Camaros and Chevelles, known as COPOs, not only for Yenko, but other dealers as well. Not for sure what reference material you are using, but this is well documented in almost all reference materials dealing with high performance musclecars.
Here is a Yenko ad from 1969, listing the 427, 450HP as available with either 4 speed or auto.
