I decided to put a new gasket on the exhaust and intake manifold to the block.I then decided to install a new gasket on the exhaust flange out to muffler.I turned manifold upside down on the work bench and noticed there is no heat riser only stove bolts in the holes where the shaft should be. I do not know how long it has been like that but i am sure DAD must have done it 50 years ago. Should i just leave it be or install a new one? Engine runs well on trips on the back roads (joy rides). Any feedback .Thanks