does the one on there have the thermo spring on the front of it?

most likly some one done swaped a diff modle clutch and fan on it to get the 7 blades

could be your prob if it not a thermo clutch

as far as locking up at speed and roaring

non thermo just wont do it

I would just replace the thermo clutch with a new one from napa,mine was 65$ and you can hear it when the temps creep up,idle or speed

the right shroud is important also,the blade needs to stick 3/4 of there width into the shroud