Creating a TOC from mulitple Word Documents in Word 2003

I work with training manuals that have to be constantly updated. Besides Headings, is there a way to make a TOC for multiple words files used to create a Unit within my manual?
The problem I have is we use many word documents within the unit rather than on big doc file. It helps hold down all the reformatting when deletions occur.

Thanks in advance,
Beau