Exhaust Leak - 318 Manifold

[ClarkDart70]

Ok, so I have been fighting a phantom exhaust leak at either my manifold to head gasket or the manifold flange to downpipe. I just ordered a set of remflex gaskets for the manifold to head gasket because I have heard great things about their products... my dilema is what can I do about the manifold to downpipe flange?
-Can I use a donut?
-Do they make a special flange seal for this?

The previous owner gobbed a bunch of copper high temp perma seal in there before, but I'd rather have something a little more durable than that. Any thoughts?

This is for my 70 Dart.... 318, stock exhaust manifolds, LA heads, dual pipes with one down pipe off each manifold if it helps.

Thanks,
Clark

 

[jarvitron]

I'm sure there's a "right way" to do it, but I've seen flange gaskets and donuts used. There's a set of flange gaskets in my Fel-pro set which I plan on using, but when I pulled the exhaust off, there were some (completely dessicated) donut seals in there. I think my plan right now is to use some "ultra copper" on the flange gasket and around the manifold "ball", I've done that before and had good results as long as you alternate tightening the bolts so it goes in flat.

 

[blackbomber]

I'm not running any gaskets on my downpipes, and they don't leak. The way it's designed, I think trying to add something there may invite leaks, but I don't know. Put the other gaskets in place, and see how that works.