Looks like you might have chipped a tooth there...
x2.....time for a dana ya got to love them 4speeds...............ArtieAlso looks a little like the pinion depth was just a bit off.
Look at the shiny wear pattern on the ring gear teeth just to the right of the broken one.
Notice the pattern is close to the outside of the teeth (Same area that broke off the tooth)
It's pretty darn close to perfect wear pattern, just a little off center of the teeth.
Probably a factory defect.....
On the forth tooth (right of the broke one) you can see the tooth depth in the valley and I'd say you were dead nuts and equal on the inner and outer flank.