This may not be what you're looking for, but in some old publication (I think it was the Divine Purpose book) there was an anecdote about Bethel needing coal during WW1 when supplies were nonexistant. The brothers prayed that if Jehovah wanted the Society to continue he would provide the coal. The next day some big truck full of coal showed up to deliver - apparently an anonymous donor had sent it. That was taken as a BIG sign that they were on the right track. There were several other similar stories.
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The Odd Life of Jehovah's Witnesses