The serial number starts with K, that would be 1970 and up.
The coin is flush, must be an early 1972 or earlier.
The raised button started late 1972.
Stabilizer bushing was standard from 1971 and on.
My educated guess is if there is no stabilizer bushing it’s a 1970.
If there is a bushing, it’s either a 1971 or early 1972.
-Simon