On this parts fiche the Bolt Flange 14x10 is the most specified component.
The lowest price component in this Rear Beam parts-list fiche is the Bolt,flange,10x16.
A sample from the products for the Rear Beam include: Bolt Flange 14x10, Stiff Rearbeam Lh, Bolt,flange 14x83, Rearbeam(l/h).