Interestingly, there were multiple lines of General Motors produced V6 engines. The first Chevrolet V6 was introduced in 1978 as the article stated. It had a 90deg block that was based on the SBC. There was also a GM 60 deg V6 engines produced between 1980 and 2005 and used in a few Chevy car lines. Then there was the GMC truck V6 (305's and larger) produced between 1959 and 1974. And there was also the Buick V6 first produced in 1962.
Since the article was talking about Chevrolet engines, I'd say the other earlier production engines don't count.
