Yeah, the plastic fans develop cracks, sometimes fairly quickly.
More like "checks" than cracks though, from the ones I've seen. And I don't remember ever hearing of one fail. Have you? Does anyone remember any stories of the Explorer fans failing?
Even in all the bazillion miles that Explorers were driven, I don't remember it being an issue. But maybe I just wasn't paying attention to that at the time.
I have both fans, but not sure which one I'll run. Got a plastic one on the '68 right now and will keep it that way.
Paul