Two studs inboard, who's exposed shank 9 times out of 10 will be
so eaten away by rust from heat and moisture that they will
snap off.
And two bolts outboard, which if soaked over night usually
can be persuaded to back out.
If you're pitching the exhaust manifold then no sweat. But if
you're intention is to save it, then you are in for the fun of
tying to drill out the old stud stump. Got to be on center or
you will damage the original threads. Here is an example of one
that someone tried to drill by hand and got the hole off center
and wallerd out:
http://www.pbase.com/dennygraham/image/136491216This required a fixture and the addition of a Helicoil to
straighten it out:
http://www.pbase.com/dennygraham/image/136491494Lots of work but it corrected a poorly done repair and made a
usable manifold out of a cadaver:
http://www.pbase.com/dennygraham/image/136491556Denny Graham
Sandwich, IL
