Heuer Solunar Watch

Beautiful example, not sure if there will be much information here unfortunately as it's more geared towards modern TAG. And essentially the only information I can give you is that this model first appeared in 1949 - I can't seem to find a definitive date for end of production, though it seems there were not very many made so I think it's a safe enough assumption to say your watch is most likely from the early 1950s.

You could try the On The Dash vintage Heuer forum, someone there might be more knowledgeable about serial number ranges.
http://chronocentric.com/forums/heuer/