yeah it'll be on the transmission, closer towards the output shaft...but don't just throw sensors at it, do some basic diag first, and if all else fails, talk to someone at the stealership
try and stay away from outside shops, as most of them are really grimy and desperate for money, so although you may pay more per service at the dealership, you'll get techs trained extensively on the 15 or so Toyota models and you wont get something like,
"well we replaced the speed sensor, but one of the lights are still on, so we need to look deeper into that. but while we were in there we noticed that you need brakes on all 4 wheels as well as new tires. also your muffler has a few spots of rust on it so we need to replace the entire exhaust system and your wipers are brand new so we'd like to replace them as well"