Removed front differential cover and found 3 teeth missing on ring gear!, pinion is somehow still intact? No wonder it drove better in 4wd!! IT STILL CAN OPERATE IN 2WD!

1) Is this a "weak-link" on these vehicles?
2) New ring & Pinions available?
This is my Idaho backcountry backup vehicle, so it is worth fixing up, I have the factory shop manual, what are some recommendations as to fixing and some possible mods for backcountry mountain switchback driving? I am 60miles NE of McCall, ID on Southfork of Salmon. Thinking of buying a parts car and O/H the transaxle then swapping, open to suggestions!
Thanks,
Doug