Thanks for the helpful responses, but I think I
wasn't clear in my question.

Studs seat in the flanges of the crossover pipe.
When installed, they point forward and go through
the holes of the exhaust manifold flanges.  Then
a washer and copper nut.  VW has nuts that are
12 mm outside.  Busdepot (and McGuckin's Hdwre
in Boulder) have copper nuts (self-locking) that
are 13 mm outside.

Some recommend using antiseize so the nuts can
be removed more easily in the future.  What
I'm asking is about the studs seated in the
threaded crossover pipe flanges:  Should I
try to lock them in place with a compound other
than rust?  The studs in the old crossover pipe
are going to come out without major efforts,
and new studs are 55 cents each (31 mm length.)

Another question:  I see evidence (red stuff) of
some kind of gasket paste along with the metal
gaskets between the crossover pipe flanges and
the manifold flanges.  Is that just because my
mechanic reused the old gaskets when I got my
Boston Bob engine or is it good practice to use
some kind of compound there along with fresh,
new gaskets?  I would think a new gasket is all
that is needed.

BTW--Mr Bus came home in late January, 1982, and
so is 20 years old.  The original exhaust was
replaced with VW dealer parts in '92 and now
with Busdepot parts in '02.  I've used muffler
mud to keep the crossover pipe sealed up for the
last year, however....

Thanks!
                         Richard A. Jones
                         Boulder, Colorado
                         '81 Vanagon   Mr Bus
                         '87 Syncro Westy   El Jefe