Ref:
http://www.funcat-sailing.de/Tornado/sitebeamsbeschlaege.htmLook for the aft view of a Tornado rear-beam, there you can see the rivets you need.
You can order them from these guys, in Germany, or:
http://www.catsailing.net/shop/rearbeam.htm also in Germany.
Otherwise, you can go directly to
http://www.marstrom.com, and order them there from his webshop.
I dont know which of these will respond quickest, but I have mixed experiences buying small items directly from Marstrøm.
If you are desperate, forget about the rivets and make your own SS hooks, thread the other end of the hook and bolt them with some nylon washers and a lock-nut on the front side of the aft-beam. Requires some fiddling with battens inside, to tighten the lock-nut, but lets you raise the trampoline a bit since it dont have to go under the beam anymore.
If you find similar bolts/rivets, they are probably not in monel, but with a alu house and steel nail. The nail will quickly rust and the fitting will break.
My best tip, order some from the guys in Germany.. I think Wolfgang Heineman works for Catsailing, and he is a nice guy to deal with.