In many respects, the factory 7-blade fan was not that noisy to me. When started, it would make some "fan" sounds, but in a few seconds, quiet down to nothing. That was the way the OEM and later DANA/Spicer replacements did, too.
Not sure about the HD versions, but when I was seeking to not spend money (I didn't want to spend at the time) on a new fan clutch, I discovered that I could dimple the outer "oil reservoirs" on the front (with a blunt Phillips-head screwdriver) to increase the internal pressure and more "lock-up" the innards so the fan took longer to uncouple. I could hear it up to about 30mph in low gear, then the air coming through the radiator would overpower it and it would quieten down.
At the Chevy dealer I worked at, in the summer, sometimes we'd have customers come in and complain that their 454 tow vehicle's transmission was downshifting too much. Turns out they were hearing the clutch fan cut in and out.
So, drive the car and see if it doesn't quieten down after you get to about 35mph or so.
One time I didn't want to buy a new fan clutch (see above) and put a Flex-A-Lite stainless steel flex fan on the '66 Newport Town Sedan. It WAS loud. Sounded like a jet getting ready to take off at 60mph on the highway! Tried spacing it in and out of the shroud, no help. I could take the air cleaner off and not have to worry about burning my hands after an hour drive on the Interstate at 70mph in TX July heat. It was moving THAT much air, but not increase in mpg from it pulling the car down the road! Ended up taking it back for credit and reluctantly going back to an OEM Dana fan clutch.
Just my observations and experiences,
CBODY67
