Just a thought on the issue of corrosion between the guide plates and the aluminum head bosses; I don't know whether it would hold with this application, though; on electrical connections, especially where dissimilar metals are involved, I have always used some sort of anti-corrosion grease when making the connections up. In high voltage work, we cleaned and greased all connections, and then tested them for resistance before energizing them; bolted connections were especially critical, clamped ones not so much. Now, I can't say that anti-corrosion grease, brands I can think of right off the top of my head are "Anti-Cor", and "No-Corrode", would be useful or effective in an engine where aluminum and steel or cast iron are in contact under pressure of a bolted joint, but it is something to consider; perhaps a heretofore un-considered alternative to anti-seize.

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