95 454 Exhayst Leak

[Blazer Eagle]

First off....exhaust*
I'm sorry, I noticed my typo too late. Anyways...

Last June I had the donut gaskets replaced on my 95 454. All stock as far as the exhaust is concerned. This fixed most of the exhaust noise I was hearing, but there was still that annoying exhaust leak tick tick tick under the floor board. I assumed that meant I had a cracked manifold.

Fast forward a few months and 12k miles to now. The exhaust leak is back with a vengeance. It's so bad I have to shut the truck off to order from a drive through. I had chance this weekend to poke around for the cause and found that the donut gasket on the driver side is blown out again.
I also found, a crack in the manifold as expected - what I didn't expect to find was a sheared off bolt.

What would cause a donut gasket to blow out so soon?
Can the broken bolt be extracted without pulling the head?
The passenger manifold has a small crack too, if I replace both manifolds should I go the extra mile for headers?

Thanks for all your help, I'm just trying to decide what the best route to go is

[Palf70Step]

I am sure you can drill one out, I have never tried , ate least not while it was on the engine and in the truck.

I have done this. Once you take off the broken manifold, I welded a nut onto the bolt that was in the head. There was just a tad exposed on mine, I for a nut just big enough to fit, then I welded the nut on. I am guessing the heat helped some, but I was able to work the bolt out.

Not sure what replacement headers (good to decent ones) cost for a 454. IF you do go with headers you'll need to modify the rest of the exhaust and may nned to get some new O@ sensors for the headers.