i have the short hayden clutch. i was just changing fans. i'll send the 315 out for powder , i put teh 5 blade onand it moves some air. let it idle in my garage and the gauge moved about an 1/8 inch after 20 minutes.. much better then before.. i will run this 5 blade and if i'm happy with it it will stay.. if not i'll put the nice 7 blade onit.. i will say the 5 blade is so much easier to get to the bolts to put them started..lol