How long have they been making Chevy 350 5.7L engine?

The Chevrolet small-block V8 engine, which includes the 350 cubic inch (5.7L) version, has a long and complex history with numerous iterations and variations over the decades. There's no single "start" date because the design evolved.

However, a good approximation for the start of widespread production of the 350 (5.7L) as a distinct engine offering would be the late 1960s. While earlier small-block engines shared the basic architecture, the 350 became a very popular and enduring option around that time. Production continued with various modifications and updates through the early 2000s, though not always continuously under the same designation. So there's no exact end date either.