Just an FYI that may or, or may not help someone else.
I hit a junk yard last Friday. I picked up a stainless flex fan, and a factory 7 blade.
The flex fan was a step down from the 5 blade I had, 1/2 hour on freeway put needle to top of range, no improvement in stop and go traffic. Glad I did not pay full price for the flex fan. I would not recommend a flex fan based on this.
The 7 blade, although it sounds like a B-52, and stole some HP, seems to have solved the problem. Took a run out to the desert on Saturday, 115deg, AC on, gauge at what I think to be about 195-200 deg. Prior to the 7 blade a four hour trip like this would have required two stops to cool off. Stop and go around town (@101 deg) yesterday had the gauge indicating it was running 180, right on the T'stat. Cool indeed.
There were 4 or 5 Mercedes in the yard, some V8 and some diesels. I saw the slim line clutch fan units, but was short on funds. I had previously removed the pump mounted fan, and ran an electric, (gave up due to electrical issues) and gained about 2 MPG, so I like the clutch idea. Maybe later for a clutch.
Not hot Ross.

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Ross Rither
1964 Dart, 170
225, super six.