The coolant drain on the radiator is on the lower passenger's side.
The coolant drain on the engine block (3.4L V6) is on the passenger's side at the front side of the motor mount, right between the two front motor mount bolts. Its a brass plug with a 14mm head. You can reach it through the wheel well with a long extension.

'97 4Runner, '06 F350, '86 4Runner, '05 WR450
http://home.4x4wire.com/erik