Here is a nice one with pierced lugs on a L9 "patent pending" casing. Doesn't look like it had much wrist time and is keeping perfect time. Based on ad dated 1959, calling out the "NEW" Sea Kings and linebooks, it looks like this one appeared in 1959, and had a dial change mid year, keeping the same variant designation going into 1960.
1959 Sea King "IW"
April 1959 ad shows the watch with a gold dial and calls out "also with white dial". Matching 1958 - 1959 linebook136 is below, as well as 1960 linebook139, showing new "fish scale" dial.