With my own two hands I've taken a mazda tranny out of a 4.0 v6 Navaho, a rebadged ford explorer, and got some rebuild parts from a wrecked ranger with the same engine/tranny.

The main failure point in the fm/km145 is the input shaft spacer plate for the bearing. It gets pounded out and lets the bearing and shaft wobble. Almost every time I have exposed the input shaft on this tranny, you can wobble the shaft a bunch if the tranny has more than 100k on it. The rest of the tranny seems to hold up pretty well. It was used behind the starquest 2.6T and had to be beefed up in the above area to handle the higher torque. Even with that, the engine was confined to a lower boost level in the lower gears...