Was your grandfather’s store on Margaret St. in Plattsburgh?
If so, there is an item on ebay right now
http://www.ebay.com/itm/1932-COVER-PLATTSBURGH-NY-A-H-MARSHALL-CO-WHOLESALE-HARDWARE-/301585241370?pt=LH_DefaultDomain_0&hash=item4637e1951a
Yes,My grandmother Dorothy M. Johnson was a Marshall and she married Nelson f. Johnson.