For the fan, just pop the hood and check it out. A mechanical fan is bolted to the front of the waterpump at the front of the engine.
The gears is a little tougher. There might be tag on one of the bolts that holds the front or rear differential cover. Otherwise you can manually check it or look up the VIN here
Comprehensive GM VIN Decoder
My 2006 has electric fans and a 3.42 axle ratio. I can easily get 17 on the freeway right now with my topper and the weather.