Ken, is there a crack in the middle between the flanges? That’s where they usually crack. As we all know, never use silicone sealant where gas is in contact with it because gasoline dissolves silicon sealant.
There is a sealant called “Motoseal” that is like silicon and works great on these gaskets, even if they are cracked. Just coat the entire inside and get between the flanges on the outside. It is gasoline resistant.
I use Permatex Aviation form a gasket where the gasket meets the manifold and turbo housing. It is gas resistant also but will allow removal much easier then Motoseal.
Most of these flange gaskets get ripped in the middle upon removal from the manifold when they stick to it. I use a thin feeler gauge to push in to the gap between the gasket and manifold to pull off the turbo.
These foot flange gaskets really need to be reproduced.