Don't do an electric fan conversion. It's not worth the effort. Your stock belt-driven fan, provided that the fan clutch is working properly, should do an adequate job of both cooling and minimizing power loss. I used to run an e-fan on my other 4x4, and my alternator decided to die while I was on a 4x4 trip 3 hours from the nearest civilization. I had to limp along only on battery power, stopping frequently to get a recharge boost from companion vehicles until our group reached civilization the next day where I could make repairs. It is risky to rely solely on the electrical system to keep the engine cool on a 4x4, especially one with a V8.