They are not all 986D460. But they are all xxxD460, which cannot be an original serial number, as the originals were sequential (xxxD460, xxxD461, xxxD462, etc) What remains constant (or close) in the original serial numbers is the first three digits, as one would expect in sequential numbers. This is true across the entire Zenith catalog for that time period, every model, no exceptions. That is how we are able to determine 5 production sequences for the A386, as follows
538Dxxx - 539Dxxx
707Dxxx - 708Dxxx
861Dxxx - 862Dxxx
922Dxxx - 923Dxxx
231Exxx - 233Exxx
So there's a small series of original A386s with serial numbers that are not only different, but conceived and organized differently from every other case number in their entire production?
I do find it believable that Zenith made these, given the quantity and consistency of the examples. So I read it not as a restoration, but as a modern assembly partly from the parts bin (old movements, old cases), and new production dials and hands. We know we've seen these new dials for sale loose. The old cases did not have serial numbers as they were never used in production, so Zenith cut new ones (even the technique is different from the original etched ones). There are other examples of such "new-old" factory assemblies among the Swiss manufactures when they want turn legacy parts into cash.
Everyone is of course free to make an individual judgement about authenticity, originality and value.
As for the Zenith extract, I'm interested how they establish a production date for a serial number that could not have existed. Or perhaps they use the same methods as Universal.