Rearend Took a Dump. How Bad Is It?

I first noticed something wasn't right when I turned corners from a stop and it sounded like I had run over a big pop can. Didn't know what to make of it. Till yesterday. Turning right from a stop sign, there were these two SEVERE bangs from the rear of the car. I thought at first the guy behind me had hit me. Drove home normally. Popped the diff cover and found this....

I don't know much at all 'bout car rearends, but this can't be good. What to do? Replace whole rearend, just the roached gears, have it rebuilt. I have exactly 127 miles on the 904 I just learned how to rebuild. Was really hoping to drive more before the next major issue. Oh, car is '68 B'cuda FB. Rearend is a 2.76 pegleg 7 1/4.

Please advise.
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