With the rear exhaust it is held in place by a spring that wraps around the crankcase. On this one I am using a AE Factory Team rear exhaust. I also ordered a "generic" rear exhaust off eBay from a guy in the UK for another engine I have. He lists it as a Associated NTC3 Shiny Inline Rear Exhaust Pipe Manifold. I paid about $15 so I figure why not give it a shot, it comes with the manifold, pipe, spring and gaskets! Have not received it yet but I didn't want to spend the $$$ for another Factory Team setup.

I took some pictures for you so you can see the setup I am taking about, hope this helps you.