I've searched the Internet for a similar post but just can't find anything similar to my problem.

​​​​​I have a 1997 4Runner that has a clunk when overdrive is engaged. At highways speeds, RPM's below 2k, there is an obvious clunk when I give it more throttle. When coasting at 60-65 and accelerator is pressed say for a hill or more speed, I can feel the clunk. The car has 330k miles. Just wondering if my transmission is on the way out or if it's something I can fix/ manage. Thank you.