Hope everyone is have a good Friday!
I have not posted in awhile which I guess is good, no issues with the 4runner!
I’ve had my ‘00 since 2005 and it has 305k on it. It’s been great and is still my daily driver, it’s like an old buddy haha

I’ve had the trans flushed twice over the years. About a month ago the 3rd shifter hesitated and slammed into gear. Had never done that before. After I noticed a low whine when it got into the 3rd shift (usually around 35-40mph in normal driving). Fluid looked fine. The hard shift didn’t occur again for about 2 weeks and that day it happen happened a few times.
Took it to a local import shop and they said can’t do much now unless I want to have the trans rebuilt for around $3500. They didn’t drop the pan or inspect much. They did say the throttle cable was loose and tightened up.
The whine has become a bit worse after the 3rd shift point.

I did some searching and it seems could be the planetary gears or torque converter?
Any advice or just keep driving it till it become hard or unsafe to drive?

Thanks!