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