So some lame-o really botched the Y pipe replacement job on my DII when the previous owner had it and I need to fix an exhaust leak between the Y pipe and intermediate muffler.
I have seen multiple sites with NOTHING there, the rave manual appears to have a flat gasket between the two and rovers north has a diagram of one with a donut type gasket, but when you go to the actual parts diagrams there is nothing listed!!
On atlantic british they sell a muffler kit with only one gasket for the tail pipe to muffler!

My car is leaking water at this union, so i know its leaking gas. What is supposed to be there?
If the rave shows a flat gasket but mine has a donut gasket, how accurate is the 18 ft/lb torque spec?

 

I do not believe there is a gasket between the Y-pipe and intermediate muffler. I had a leak there also. What I did to correct the leak issue.

Loosen and remove the flange, get a wire brush and clean both mating surfaces completely. Then, re-assemble, torquing the flange nuts, substantially. Be careful, not to snap or strip the bolts. This should do it for ya.

 

well RAVE says to torque to 18 ft lbs...so idk if that is gonna fly

 

I also used muffler and tailpipe sealer. I think it's manufactured by Permatex.

 

There is no gasket, because it works like a compression fitting. After cleaning the surfaces with fine sandpaper, it revealed bump at the pipe end (what looked like a manufacturing error). Smoothed it out with a file and sandpaper and my leak was gone. I guess the bump caused it never to seal properly.