The Translation Wizard on this site is useful to translate individual numbers. Complete HTS-NAICS concordance files can be purchased from the Census Bureau as part of the monthly trade CDs. Go to
http://www.census.gov/foreign-trade/orders/1210.html to order.

To learn more about the NAICs systems, please go to http://www.census.gov/epcd/www/naics.html. Trade by SIC codes is available through the year 2001. SICs have been replaced by NAICS codes which are available from 1997 to the present.