If you are talking about the front metal rod that will be encased in the fabric sewn to the new top, it's ends are riveted to the two longitudinal fabric pieces. It is a sort of odd design. I think the weight of the rod suppresses flapping of the top when at speed.
These longitudinal pieces are always too rotted to reuse. A good fabric store should have a good selection of these in various colors (they will be on large rolls, and you pay by the yard). You won't find an exact match for the old ones, but you should be able to get close.
I use rivets I got many years ago from Tandy Leather Goods. They are probably available from shoe repair shops, too. They are brass-color and easy to use. Just smash them between two hammer heads.
Joe
