There is a tool to hold the pulley from behind and prevent it from turning while you removed the bolts from the pulley. That of course is done after you remove the fan. Once forum member posted this picture...
http://f1.pg.photos.yahoo.com/ph/tabijan/detail?.dir=/1e6b&.dnm=e7da.jpg&.src=ph
I hope this answer your question.

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J.H.
'86 300E