Maybe you could consider fabricating a subframe that would tie the loader mounts to the front of the tractor as well, so the forces of the loader would be so concentrated on that broken area.
Bingo, that's my next move to reinforce the weld area. Thinking 2x2. .250 wall aware tube and some plate to link rear axle then I'll figure something for the front
I've seen plenty of tractors had a frame supporting the loader to the rear and front, not sure why this one didn't. Anyone know the technical name for them so I can get some ideas? Can't find anything aftermarket for the tc35da so I'm probably going to have to Fab. One
I don’t know the technical term other than some are called full frame loaders. Some backhoe subframes have a C shaped mount that catch 3-5 of the bolts that attach the rear axle housings to the rear axle center section. That may help you design your reinforcement.
I went through the parts manual for my tractor and took a couple pictures on they do on most tractors. Maybe it gives you a couple ideas to work from.
Here is a picture of the subframe. It bolts to the engine block and the axle will mount on the subframe. Left is the front of the tractor and where the front weight bracket bolts to.
Then, this is where mine is different because I have a mid mounted ROPS. But the loader mount will then bolt through the subframe to the engine block and also bolts to the bellhousing, tying everything together. Then two rails go from the loader mounts to the rear axle.