Longest KMs on one I've owned was 20k. Never hung donuts in it not a fan of them.
Singled twice due to lack of torque , third gear entry in a V6 ute before the blower was on it in the dry. Scandoed in fine but ran out of power on the exit.
I can't turn one wheel by hand without absolutely struggling with one on the floor. But I do shim them to the point they skip in car parks the first thousand KMs.
If paying to change the ring and pinion I wouldn't bother for less then 3.7's.
I usually sell whole lsds with 3.46 for $250 if you pick one up keeps your car running and then only need to count the turns in and out on the side carrier bearings to reset mesh after tightening the LSD.