Engine number interpretation please

[tlc356]

A friend bought from a dealer who told him the engine in his 2005 Boxster S is a replacement from a 911. The number is 01668641533.
I believe the third 6 in the string says the engine is from a 2006.What does this tell us?

[JFP in PA]

Try this:

[tlc356]

Thanks JFP. I guess it not a 2005 engine since the third number is 6. He was told it's a 987.

016-68641533.