Rick,

I can't really say with all certainty that these Zodiacs were made by Heuer, what I can say is that in my opinion, everything seems to point that way. From the fluted pushers, serial number between the lugs, to the design/style of the case. I just can't see how Zodiac would make a chronograph case using all those bits of design, instead of just being original.
The case on this one reminds me quite a bit of the one housing the Heuer Jarama, but in my opinion the Zodiac is a much better looking timepiece.

I have never owned a vintage Zodiac, with its serial number between the lugs, and they made quite a few of those, but their chronographs all do.
I love the way the Zodiac sits on the wrist, at 43mm is 1mm larger than an Autavia 1163/11630, but it feels much more comfortable than any automatic Autavia. It is definitely built right.

I have talked to quite a few Zodiac collectors, and most of them seem to believe the Zodiac/Heuer connection is nothing more than a story made up by someone trying to get more money for their Zodiac chronographs. I agree, some unscrupulous sellers do that sort of thing, but in my opinion, the truth is plain to see.
I went on vintagezodiacs.com a few times, until I learned I wasn't really learning anything there.

One with a faded dial...

And one that looks quite a bit like a Heuer Carrera... Hmmm... I wonder how it turned out like that...

Regards

Darwin