The differences are: The addition of P*7 self-cleaning, and the deletion of the windowed oven door seen on the J326.
This one could be earlier or later than '71 - there is a notice in the '71 full-line catalog that some changes to the range lineup's styling would be happening on April 1st of that year.
There is a very similar range, the J329, billed as a "Low Cost P*7" range in the catalog.
Even though I'm looking for a GE P*7 range quite a bit higher up in the model line, if this range was sitting here locally, with no shipping involved, I just might say, "Oh, what the hell," and live with it for a while.
It's nice, even if it isn't TOL or even really MOL.