The problem with aftermarket "one size fits all" is that it is a hit and miss situation. Sure some vehicles may take the fan and operate fine and others will not. We gotta stop and think why engineers actually bother to calculate things for the vehicles or engines they are designing. If any fan was every fan in 1949 there would be no difference from Lincoln to Kaiser. But there is because engineers caluclated pitch, blade number and blade length, tip sweep and weight. They made them for effeciency in producing the best cooling at all RPM, low noise and using as little HP as possible.

I can tell you for sure a fan that does all of that for a 230CID 49 Plymouth 6ain't gonna do the trick on a 359CID straight eight flathead Packard or a 331 Cadillac V-8!

What goes for a 65 Chevelle with a built 396 has nothing to do with a stock 49 Plymouth which ain't a hot rod in any sense. It's a vintage car.

How can anyone tell their flex fan works short of a dyno session? If it don't overheat it's working we guess. Well if it's a big deal is it running cooler than before? Can you tell if it is quieter and does that even matter on the mill you're running? And the big advertised payoff- how much extra HP is it producing? Could it be as much as 3HP? Is that noticible even on the dyno? Anybody that believes statements like "10 HP increase" or "10% better fuel economy" has to realize that any performance increase would certainly vary relative to the application. Don't believe the stuff that comes from sources that tell you magnets inprove gas mileage or spinning dealies in your aircleaner give more HP. It's ludicrious.