you need a minimum of 2500 CFM's from the electric fan.
I would highly recommend getting a Taurus electric fan and a Spal FAN-PWM controller for it (you will also need a 40A SPDT relay to run the Taurus fan with the Spal controller). It pulls 4500 CFM on the high side AND it has a shroud that covers 98% of the radiator
, which is more than enough for a Ranger. I can actually watch the temp gauge drop when the fan kicks on. My tranny temps stay at around 150* constantly now also (temps read from inside the tranny). you can feel the air being pulled through the radiator from infront of the grill.
Optikal Illushun has them at his house he would sell you. You can probably get one from him for $20 or so + shipping. The controller runs $70 shipped (and is WELL worth it).
Here is the pictures from my install:
here is Spal's website:
if you need any more info, let me know! i got a wiring diagram for the Spal controller and Taurus fan also.