Unfortunately, a trip to your local mechanic is required. Try to find someone who specializes in electrical or Land cruisers.

What is the battery voltage while the engine is running?

14.4 as measured by Oreillys

That is within specifications, but could still be an alternator issue. Why you had to replace the harness is a little concerning.

We have put 4 alternators on this rig. 3 from Oreillys (one burnt through the harness) and the last one I purchased was from Toyota.