Hard to tell, but definitely up to a 1962 version. '63 was when the thumb tab was added to the latch plate.

I believe 1965 was when the latch was added. I have seen plenty of GEs from 1963 and 1964 without the protruding latch. In 1965 they were silver with the thumb latch, then in 1966 the gray paint was introduced. My 1965 GEs with the thumb latch also have a notably brighter silver patina.