Check page 8 of http://www.toyotatundraforum.com/pdf/A750E.pdf
It shows the A750E/F auto transmissions (5-speeds autos in the 2nd gen V6s) as having transmission warmer that circulates coolant around the tranny to bring it up to normal operating temp quicker. But this manual was posted on a Tundra site, so I don't know if it necessarily applies to our Tacomas. Anyone know?
I'm thinking of adding the Toyota OEM block heater for next winter. I'm theorizing that it will help my gas mileage as cold engines tend to get worse gas mileage (have another post looking for data / experience on this) & I make a lot of cold start, short trips.
But I would also guess if our auto trannys do have the warmer, then in cold / very cold climates, a block heater would not only benefit the engine, but also the tranny by bringing it up to normal operating temp much quicker.