You could try this guy. It may just be an old parts listing, but he may still have something. http://www.hobbyclub.com/index.php?cPath=44_74 Maybe a European supplier like Just Engines may know/have something as well. Exhaust screws are just normal metric threads and are available at many hardware stores or mail order outlets. Exhaust manifolds break because of the heavy mufflers that stick forward and are prone to breaking. I would just go to a swept back Macs muffler or pipe. Bisson has some nice stuff too. Other OS or whatever mufflers may have the same bolt pattern.