66 cutlass- factory manifolds w/ dual pipes (& blockoff plate)

Should the headpipes have donut gaskets between them & the manifolds, or just a flare on the end that gets pulled up to the manifold?

probably a stupid question... but this is the first classic car i've had W/O headers.

My exhaust has been leaking, getting slowly worse as i've been driving the heck out of hte car this summer.

Doesn't appear to be leaking out of the manifold to head connections- so guessing its the headpipe to manifold connections.

Drivers side is loose enough i can wobble the pipe 1/8 side to side.

Bolts are rusted tight, so it'll take a couple days of pb blasting them before i can try to just tighten them up- but If its a missing or deteriorated donut gasket, tightening them won't help, so thats why i'm asking :-)

thanks!
Ben

edit... also-
there appears to be some sort of butterfly valve on the drivers side manifolt that is wired open... what is that for?

 

The butterfly valve should have a thermostatic spring on the outside of manifold. This is used during cold start up. The valve closes and forces the exhaust heat to build up inside the exhaust crossover on the intake manifold and for the heat stove. I had a valve like this on my 64 98 that was seized. I just took the manifold off and used a grinder to remove it.

Olds manifolds either have a built in "donut gasket" or they need one insterted in between the manifold and the pipe. Once you get the manifolds off you will easily see if the gasket is cast into the bottom of the manifold. It isn't gasket material it is just and extension of the exhaust manifold. If your exhaust is leaking in between the manifold and the pipes and you have the "intergrated gasket" just have an exhaust shop reshape the pipes that meet up to the manifold. They could have rusted and deteriorated with time.