The ebay listing below shows an example of OEM saddlebag mounts for the XS 650 that I've not seen before nor knew to exist.....
http://www.ebay.com/itm/YAMAHA-XS650-FACTORY-SADDLEBAG-MOUNTS-RARE-/290639796460?hash=item43ab7b58ec&item=290639796460&pt=Motorcycles_Parts_Accessories&vxp=mtr...