Fan clutch install 72 GMC C15 350

[huntznsam]

In the hopes of just a tad more MPG, I installed a fan clutch to replace the fixed 7 blade fan on our 72 GMC C15 350. Yowza! MPG takes a back seat to quiet. At idle it is world of difference; on the highway I’m no longer hesitant because of the old jet-engine roar at 65mph. It sounded like I was turning 6000 RPM. I was blaming the 3.73 gears. Heck no – it was the fan!

Now I hear a rattle that needs attention, and the exhaust leak that was trivial is now more prominent.

I used the following:
Fan clutch=AC Delco 15-80245 (Amazon)
Fan blade=Dynacorn M1017 7 Blade (Ebay)
Water pump studs=Dorman 675-001 (Summit – correct 5/16-24 fine thread on the short end)
I had the balance of the hardware in my bins.

The fan sits just right, about one inch out of the shroud. I haven’t driven long enough to hear it kick in, but I don’t expect trouble.

Thanks to the experts here for all the good info – I got the part numbers from you. I hope this is useful to the next guy.

I’m a serious tracker of MPG, more for vehicle condition/efficiency than cost. I’ll see if it really makes a difference.