2002 Subaru Outback w/ 137k - viscous coupler

I have 137,000 miles on my subaru outback. Back around 80/90k miles I had a bad pair of tires and turns out one was larger then the other 3. The car pulled left or right depending where that tire was. I got that all fixed but drove on the problem for a few thousand miles.

So fast forward to now about 10k miles. Once the car gets hot from highway driving there is a loud “clonk” noise when I turn sharp and it requires some extra power to turn into a parking space. The problem is really noticeable driving on the highway to work and then making a sharp 90 degree turn into a parking spot. Its a loud clonk…clock…clonk… as I turn in.

I’ve been on a few long road trips (4 hours of driving) this spring and plan on going on a few more this summer. The car is fine on the highway its just a problem turning sharp at the end of the drive.

I’m thinking the viscous coupler needs replacing. Do I get this fixed? Its really not that big of a hassle to just have some noise and a clunk at the end of a long drive. But i’m worried this is going to cause something else to break.

Is the car safe to drive on a long road trip?

Also how much should I expect to pay for this repair?