Jeff, excellentas !!!
personally prefer the Carrera 45, only few years in production and absolut beautifull with the red printed tachymeter scale ref 3647T all I have seens carry early 73/74 serial numbers some with heuer crown some without.Interesting also the carrera deci 3647D.
Rarest of all carreras believe is the Date at 12 in black or silver.Would compare it to your dato valjoux calender eg rated at 3.0.nver saw these in a catalog only one add exists.
The valjoux have been produced for more than 10 years still apearing in the 71/72 sales brochure.
The Carrera 45 only until 66/67 as far as I am informed, hence believe tey are definetely more rare and possibly undervalued...
Whats your view guys?
Best AMH