Mopar Viscous fan??

I don't know squat about the lock-up question but I do know the reason summit and everybody else has had them marked down in price for the last year or so is because Mopar has been selling them off cheap, I got mine from the local dealership and saved both on the price compared to the aftermarket parts guy's but there was no shipping charge either{ think I paid @ 50 bucks Canadian },just look up the part # on the Mopar Performance site and call your local parts department -easy and cheap just way i like my ladies .Now if they would only slash the price on a 440 smallblock crate I would have something worth cooling eh!8)