I am using the Taurus fan on my 2.8, and then the 2.9. It is two speed, I wired it for the high speed only. I also have a mechanical temp gauge, when the fan kicks on, I can watch the temp needle fall right down till it cuts itself off. This is on the hottest days.
This is the temp switch I am using. It's made to directly control the fan power. I first used it when I bought aftermarket fans at the store. I bought a 16 inch fan, and it would not keep the little v6 cool.
I then went to the junkyard and bought the Taurus fan. I noticed the aftermarket store fan amp draw was about 8 amps when it ran, it was only one speed. I then experimented with the Taurus fan, on low speed it did not draw enough air, and it only used about 6 amps of power. On high it really cools well, but it draws 10-15 amps of power. I was afraid this would be too much for the temp switch I bought, so I kept using the same temp switch, but I use it to activate a 30 amp relay. The relay does the work, the temp switch just has to turn the relay on and off.
I also wired it to a ignition on wire when I went to the relay. Before I just went from the battery to the temp switch. So when I turned the truck off the fan would cycle by itself as the truck got hot just sitting there with no coolant flow. But this never seemed to hurt anything and never ran the battery down. It only ran a few times before it quit running altogether. Some older cars were like this from the factory.