Another weak point is where the articulation hinges are welded to the engine and cab halves of the frame. Often will see them cracked and more than once pulled right apart when they completely let go. If you can catch them early, just weld and re-enforce them by welding gussets between the hinge ears and the frame. Top is the worst offender it seemed. In one situation, I had to replace the cab half of the frame as it was broken away and stretched apart beyond repair while still in the tractor. Customer picked up a half frame from the wreckers.
Welding on the axle oscillation member is common, not often you will ever see one of those with a loader without some welding on the frames somewhere or even a broken housing. No probs if its just used as it should and within its ratings, but when trying to move two large bales or such at a time and the engine end coming off the ground or even weighted down, that just is a matter of time before problems arise.
Was unable to source any of the ball joint type swivels they use in the pivots and ends of steering cylinders, got what needed always thru NH. Rest is just metric hardware mostly as I recall.
Just a few memories of my experiences fixing a few different ones in the neighborhood over the years