Since 7772 fans are gold plated, I went out and picked up a used 3937779 fan today. It has the offset 7 blades, thermal clutch, and measures close to 17.5 inches. From searching on the internet, it appears that this may have been for a '68 Camaro, but there is not a lot of info coming up. My shroud is a factory 19". I'm running a aftermarket aluminum radiator with a warmed over Big Block. Should I run this fan? My only other option at this point is buying a new 18" 6 blade clutch fan from Orielly's. Thanks for the help.

try it and see if it works.
if not, go find a fan off a late 80's Caprice cop car.

Looks to me that the only difference between this one and the 7772 is the fact that I think a 7772 is 18" as opposed to this one at 17.5. It has the turned down ends. The Orielly "replacement" doesn't have the offset fins and is 6 blade, but the full 18". Don't think I'll see a defference in cooling, I was just concerned about too much space between the outside of the fan and the shroud. Would that cause any difference?

Another problem I forsee is getting a new clutch. Since I can't find any real documentation on the fan, I'm not sure what clutch to purchase. Thanks.

clutches are clutches. order the one for your car. just make sure to get a decent one that has a spring on the end, and not one that goes off rpm's.

1/2 inch .... thats 1/4 per side it shouldn't make any difference
I'd run it as the factory fan with pitch on the blades will be better then some thing from the parts place without

Chad,here is a GM 7 blade 772 clutch fan on ebay ending tonight . It just needs paint and is only at $40 at this time so check it out. Search item 150087352229 in ebay to see it. (ends tonight @ approx 8pm PST/West coast time)

Scott

If you have a tough cooling problem get the severe-duty clutch. There is also the heavy-duty and regular-duty clutch.