I think that all gasoline sold nationally now has to have an ethanol
content of 10% that replaces MBTE (sp?) that was declared "dangerous" by
the EPA..  There was a big fuss by the oil companies and refiners.

JT

I use drills; heat and easy outs
Drill it open, insert the easy our and try; sometimes the heat of the drill
breaks it loose, but be careful, you don't want to break the easy out. If
that doesn't do the trick, an ox/ace torch, heat the stud hot and then try.

Per Stephen H.'s suggestion, I bought an 8 mm stud removal
socket (with the roller cams) on Ebay for $13 ($7 + $6
shipping). Over the past two weeks, and after driving the
car awhile so the engine was hot, I removed the old nuts and
applied PB Blaster so as to maybe penetrate to the studs'
threads. The stud removal socket worked perfectly on all
nine studs, including the one partly broken off. Enough stub
was left so
that it was not a problem.

Very little torque was required to remove the studs with the
socket. I needed only an ordinary 8-inch ratchet with a
little pressure applied. It seemed they might have still
been
tightened to the 23 ft-lbs specification applied at
the factory some 15 years ago! The old studs were very
clean, and all threads were in good shape. Nonetheless since
they were surely fatigued
from cyclic heating and cooling and vibrations, I replaced
both studs and nuts.

The original exhaust manifold gasket is a three-layered,
aluminum like affair, with the layer nearest the engine
having webs. The new gasket I bought is a single layer, no
webs. Dunno what's up with this. I retained the first two
layers and replaced the layer furthest from the engine,
since it looked most like the new gasket.

The three manifold-to-header-pipe stud threads are in
questionable shape at this time, from the two times now I've
applied serious torque. I'll chase them down soon and
possibly replace them.

Fortunately th was a very easy job.

Test drive was fine. With every control arm bushing set I
replace, I think the handling is improving. I think it is
worth the effort I am putting into it.

Little aside: I previously reported a seeming drop in fuel
mileage (to 36.3 mpg, a record low in the last few years)
after the one exhaust manifold stud broke. On the next tank,
the fuel mileage shot up to 47.8 mpg (a record high in the
last few years). So I think something was screwy during my
last two fill-ups. The average is close to my usual average
for this time of year.

I remain much obliged to people's input here. It's great to
learn and build, literally.