I use QuickBooks 2006, but on daily basis. I looked at the templates
in QuickBooks; they use the same mail  merge format found in Word.

You can access the QuickBooks templates using Help, or View Templates
from the main menu. Try modifying an existing template  merging only
the fields you want from QuickBooks by using the pull down link for
QuickBooks data fields that appear when the selected template is
opened in Word. There you should find your missing field data links.