YES you do. Unless you want to do it twice.
Remove intake and exhaust manifold. Remove head and replace the gasket. This is a major repair best left to a professional.
That engine has 2 knock sensors and there both underneith the intake manifold. You can not see are get to them untill you remove the intake.
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No, you need a new gasket. About the only gaskets that may be reusable are valve cover gaskets some engines.
No. which manifold gasket are you wanting to replace? Intake or exhaust?
Find $1500 dollars and go to the crooks at a Chevrolet dealer so they can make money and you get screwed up.
There is 2 of them on that engine and there underneith the intake manifold. You can't see them are even get to them until the intake is removed.
You have to remove the Intake
There are 2 of them, Thay are under the intake manifold. You will have to remove the intake to get to them.
Begin by removing the wiring harness from your 2005 Chevrolet Impala horn. Remove the horn retaining bolts. The horn will come off.
There are 2 knock sensor under the intake manifold, You will need to remove the intake to get to them.
It is located in the air tube from the air cleaner to the throttle plate.