The merger with Leonidas and the launch of the Carrera happened in the same year, 1964. As a result, there are very few Carreras marked Ed.Heuer, many of which have the polygonal caseback carried over from earlier watches. These represent only the first few months of production, movements were very soon being marked Heuer Leonidas. It's quite important to note that this had no effect on the dials though - the change in company structure can be noticed only from the markings on the bridge and potentially from the caseback, though later watches with Ed.Heuer markings often have the "standard" caseback anyway.

The change in dial furniture appears to coincide with the introduction of the Carrera 30 to replace the 45, with the changes also being carried over to the 12. From the catalogues, this appears to happen quite late in the life of the first generation Carrera, round about 1969. The early plain steel markers are replaced by wider markers with coloured inserts (white on a black dial, and vice versa). In our Carrera table, we refer to these watches as second execution dials.

I'll borrow Jeff's photo here for purposes of illustration:

The N and S at top left are first execution, with the thin plain steel markers. The Carrera 45 Dato next to them has thin markers too - it's worth noting that all 45 Datos should have these markers, even later ones. Heuer never used the markers with inserts on 45 Datos. The SN and NS on the bottom row are both second execution (you'll notice that the hands have changed too, from plain polished steel to ones with black inserts).

Now onto your watches Rav:

All three are second execution dials, with second execution hands. This would put them all well into the merged company's lifetime, about five years or so. All of them should have Heuer-Leonidas bridges as a result. Are you saying that one or more have Ed.Heuer movements? In that case, I would have to agree that they have received a new dial and handset at some point. 3 very nice watches mind!