Well hell. Recently switched back to the Mopar Performance viscous 5-blade fan (#4140063). It was cooling wonderfully. Then I couldn't slow down enough in time going over a nasty country RR crossing. The road I wanted to take was closed so I wasn't familiar with this crossing and just wasn't ready for the gnarly crown in between the rails, with a massive rut on one side...jammed the brakes at the last second but not in time, so I let up just before I hit the bu-bump at 30mph. Fan blades were apparently a little too close. Car must have flexed like a sumbitch. Pulled over immediately after hearing the sound of metal hitting and saw all my nice green coolant flowing to the earth...2947 clutch and everything had (I thought) good clearance but there was only about 3/4" between the blades and core at the bottom(can't really see the two big holes the fan made in the lower part of the core in the pic). Water pump and fan clutch ok. So. A new radiator is next on the to-do list...thank goodness for Triple-A!