2003 OB Rumble while turning

Ok, so read a ton on torque bind and not sure if it's what I'm experiencing.

First off car is 2003 Outback, 5 spd Manual, 130k miles.

During slow cornering like in parking lots I get a rumble and bit of a bind sensation, driving straight i get nothing. Happens both left and right turns

The rumble sounds like it could be in rear or center of car. I just changed rear diff oil with Royal Purple SynBlend 75w-90 GL-5 with friction reducer and there is no difference.

Both front driveshafts are new-ish and tires are all same brand and mileage.

Transmission oil is full and clean, don't know when it was changed. I've had car for three years but not a daily driver.

Should I change transmission oil?

Is center diff oil part of transmission oil like front diff?

What options do I have?

I've heard it's rare for MT to have torque bind issues,is this true?

Thanks in advance, Eric