I agree, Singapore separated from Malaysia in 1965.
People may have confused 1967 with 1965 as the first Singapore dollar based currency appeared in 1967, but Independence was two years earlier going by my stamp collection.
Before 1967 they used Malayan, Straits settlement coinage - Malaysia also did not get its Ringitt currency until 1967.
From what I know, Malaya became independent in 1957 and then in 1963 it was known as Malaysia when Singapore was annexed or joined it. Stamps show that the name Singapore was used on them from 1946 onwards, before that, it was known as the Straits settlement colony.
When Singapore left the Malaysian Union in 1965 - the name Malaysia stuck and of course Singapore was more developed and wealthier and now the Singapore dollar is worth 3 Ringitt and the average income in Singapore is 3 to 5 times higher than Malaysia. Singapore's population is 70 - 75% Chinese derived, whereas Malayasia has a Chinese community, but its only 25% of their population, which is mostly Malay and Orang Asli (Native peoples).
I love coins. Especially silver, gold and anything really old.
Member of the Royal Numismatic Society of New Zealand and the Auckland Numismatic Society