I have a friend here with a 72 Z with auto trans, that needs a new flexplate. The ring gear teeth are all chewed up. 

Rockauto has one listed for all the 280 and 280zx, starting with 75 but nothing prior to 75., Here is a link to the only they list for 75-83. 

https://www.rockauto.com/en/catalog/nissan,1983,280zx,2.8l+l6,1209394,transmission-automatic,flexplate,8608

What are the chances of it fitting the torque converter on the 72? 

I suppose you could get a matching torque converter and flexplate (they list both in the 82 stuff) if there something unique with the early converter. 

I know there are hundreds of you out there intimately aquainted with the vagarities of the Datsun automatic transmission offerings, so this should be an easy question, right? 

And happy new year BTW.

I may have one laying around, if you want me to look?

Sure, see if the ring gear teeth are in decent shape and let me know. Thanks.

Hippo Gnu ears!!!

I have a l24 with AT on it in the garage. And a plate from zx