what years were the 2ws engines build?

'00 900B with 2WS.
Mr. Haney and the other Cat Gods will be along and tell us (to the day) when they were made.
These are some notes I have saved that someone posted(most likely Mr. Haney).

All C-15/C-16 are LOW NOX from the factory. The 2WS and 1MM are LOW NOX from the factory.........the only thing you can do about this is have them flashed with a modified file, because CAT never wrote a file for these engines without LOW NOX.
All files written after DEC 99 are LOW NOX files. All engines built after the 1LW serial number in 1998 have LOW NOX files. Any of the earlier engines that have been serviced by a authorized CAT service center in the last few years should have been flashed to a LOW NOX file.