Growling sound while driving

Change the transmission fluid with Toyota Original .. you can buy from local dealer or shop online..

The growling with wheel bearing usually changes "tone" with slight change in gas.

Tires, are they good? Tires, especially winter tires can make noise

 

There's no separation inside the case; it's all the same fluid.

 

If there's no sound in the air with the car in gear; WHY do you think it's the transmission/transaxle???????????? Isn't it spinning when you had the car in gear in the air???????
I've had bad wheel bearings that didn't present themselves until you loosened the half-shaft and what about the rear axles. You running that Prius on only two wheels??????

If you loosen that half-shaft nut and push it back 1/4 inch; your wheel will wobble if that bearing is gone. The hub will also heat up, due to all the friction. Don't wait too long cause things will start wielding together.

 

Wheel bearings usually present noise loaded with weight . In air almost nothing . Now take stehscope whilst spinning carefully listen to bearing housing rt at axle penetration . You hear the balls moving round scrape scrape etc . Pull it out of ears ya hear nada .

 

I'm with Mr. saneesh8 here; check your tires first. I had a 2001 Saturn that I would have sworn had a failing wheel bearing RH side; classic growling sound that changed pitch with speed. No play or noise in the bearing when jacked up, same as OP here. My neighbor suggested I swap the front tires L-R and drive the car... Bingo, noise switched to the left side. Replaced that tire, no more noise. Turns out that certain tires will do that from wear. Saved me a bunch of grief not to mention $$. You might give that a shot; nothing to lose except a few excess calories lol. Good luck!

 

Wheel bearing.