This addon handles the header statuses for missing items. For example, if a product is deleted or disabled, it will cause a 404 or 410 header status code to be returned. This is the propeer way to handle such situations but it has never been part of oscommerce for some reason. This contribution is compatible with all versions of oscommerce though the included files are only for a 2.3.3 shop.
The support thread is located here: