What year is this /6 ?

Hi cjh that block has numbers between the first and second freeze plugs, mine doesn't have any numbers like that. The engine that I took out had numbers. I was just curious as to what year my engine is. The engine block was still bolted to the crate when I bought it for $50. I was told that it had been sitting for over 10 years, the guy that bought it passed about that time.