model year supplier invoices

[Scott Rosenthal]

Has someone here researched Benson Ford Archives to know whether supplier invoices for a given model year are stored together in a directory? If so, then is it be possible to identify all suppliers of record of a given component for that model year? I'm told (I do not know this first hand) that there were some seven different horn suppliers who furnished the 1909 Ford horn inventory. If this is accurate, and there exists a reliable paper trail that describes this, then are there not similar documentation for lamps, speedo's, windshields, etc? I would also be curious whether Ford parts were individually sourced by Ford on a per/part basis, or whether such parts would have been more likely supplied by general industrial merchandisers. For instance, hardware retailers typically do not purchase standard articles directly through part manufacturers, they contract a general goods supplier, who operates the way a commissary supplies various products to grocery and restaurant customers. Just curious.
Regards,
Scott