As mentioned above, the built-in is definitely a KDS-16. It's hard to tell from the photo if it's the earlier non-soak cycle version or the later soak cycle version. The later version added the word "soak" under the second button. It used a different timer and selector switch than the earlier one but everything else was the same.
These machines were made from May of 1968 to May of 1971. I don't have the exact date for the introduction of the soak cycle on this machine but suspect it was sometime in 1969.
The KD-15, 16 & 17 all shared basically the same washing system with only one 4-arm hydro-sweep wash arm on the bottom. The upper arm rack was introduced on the KD18 series in Nov. of 1976.