Friend of mind just bought a 2006 tundra v-8 with no owners manual and cannot find where the jack is located in the truck

I just bought a 2005 Tundra Limited and had the same problem. You will find the jack under the rear passenger seat. First you must pull the handle located on the sie of the seat centered between the back and seat protion and fold down the back part of the seat. Then pull the handle located near the bottom of the seat and close to the floor. Fold the rear seat over toward the front seat and you should have full view of the storage box in the floor containing the jack. I'm still looking for a manual for this vehicle,

Usually under the rear seat, passenger side if 4 door or extended.

Please use this link and download the user manual for tundra 2005 which is
same manual for 2006 :
http://safemanuals.com/user-guide-instructions-owner-manual/TOYOTA/TUNDRA%20-%202005-_E


Good luck...