I'm probably off base on this, but I know that most suppliers have PDF files for parts, catalogues and illustrations. If in the help section we were able to upload and download PDF files it would probably be a great help when trying to find the correct part, procedure some of these files actually come with very detailed information and drawings!
Given the bizarrely-small limits the board imposes on the sizes of attached photos there might be a problem hosting PDFs - a link to the file in another location might be better. If that location contains a copy of a file created by another party (such as a parts supplier) then you would need the permission of the copyright holder first - although I suspect this could be quietly ignored if it is a scan of a 40-year-old maintenance manual for instance.
Jeremy