The fact that you have a laundry list of engines, trannys, tcases, and axles just to hit the 300K mark proves that I was wrong about the quality of the KJ all along. They really are not higher quality than the Jeeps before them afterall.
I've heard of a hundred of these things that have spit out valve springs before 150K... but this is just nuts. You could have bought two more vehicles with the money you've put into keeping that KJ going.
This is what you call true love.
Here is one from another jeep forum that had a long commute. all original except the alternator and the ac compressor. the poster name is colorado! look him up!