I am not in a huge hurry as I am doing a 2.5 OME on the FJ45 (already paid for + sitting in shop) over the winter followed by body and paint (sweat equity).
I only know mileage was between 200km and 300km . But they were said to have been rebuilt at one point by the dealer. None have any obvious issues but mileage in a mine truck is a tough thing to assess. They idle alot waiting for the crew but get alot of oil changes. As I understand it the engines were removed due to EPA BS. I dug around to see if I would have issues in my Land Cruisers and they seemed to be OK for the 1HZ. I will put one in my 1997 FJZ80 when the engine starts to wear out.