actually going away from the stock fan has its plus side. going to this set up would allow for better cooling performance as well as less parasitic drag on the motor itself resulting in better acceleration, power, and minimal milage gains.
only real drawback i can see would be that you probably want to have the entire system on a toggle switch for river crossings. that is if you even ever plan on making any that deep. that way you could cut power so as not to short it out in the water. all though this is more hassle in hooking things up it is also an advantage. stock fans that are spinning have to fight against the dense water and make the motor feel very sluggish. this is all of course under the assumption that any of us would take a water crossing deeper than the bottom of the fan.
how do you have it activated now?
Sorry for the hijack, didn't mean to turn this into a fan thread... Sorry E.
Its good to have been gone and now see some more folks are wheeling 80's and thinking outside the box.
alternator drag does not change cause it is a fixed pulley as opposed to the fan witch is mounted on a clutch. the extra draw of current if coupled with aux lights and such can reduce the life of your alt though.
Amps x Volts = Watts
Watts / 745.7 (one HP) = HP (Electrical HP Produced by the Alternator)
HP x 15% Efficiency Loss = HP Loss
HP + HP Loss = Total HP Used