The only 1200 diff breakages I've heard of was when my brother and I were learning to drive. We learnt in the family 1200 wagon. My brother used to do all kind of evil things to that poor car. One day the diff let go, but my Mum was the only one in the car. I suspect my brothers shopping car-park 'heli's' fractured one of the gear teeth, and my Mum was the unlucky person to be driving when it finally let go. We jokingly blamed Mum for the broken diff, but we knew that my brother's to blame.
The Ute diff is significantly larger. I've got a photo with the two sorts of them sitting next to each other. The 210 diff had a cover on the back, whereas the 1200 diffs I know both had pressed/welded back plates that weren't removeable.
It's funny, but Datsun owners are very resourceful.

Cheers,
Chris