1965 is the latest I have seen, at least if it can be confirmed, and the first Singer of this late date. I have suspected a few of the Bernina treadle cabinet I have seen have been late 50s. They are few and far between, but the odd zwing arm ziggzagger with various stitch selection features turn up. I know treadles were made most of the 1950s, but not a late as 1965.