Hi everyone, I don't know if this helps with your question but here is my experience. I purchased a Heuer Autavia GMT 11630 , Serial # 31476/54 on June 05, 1975 from a long time Heuer dealer in Zurich, Switzerland. I was visiting my Dad and as usual I stopped by to see the latest from the Heuer line. The dealer told me that he had received this watch about a month ago from Heuer. If I recall correctly the going price was about 220.00 Swiss Franks. Considering that I had purchased a 1163 model earlier here in the States for US $ 135.00 , I thought that this was a good price for the latest model with mineral crystal, SST band and spare bezels, (Tachy, Decompression and 24 Hr.) As mentioned , this would not pin down the exact production date but put it in the ball park of earlier in 1975. Hope this is of some help. All the Best. Heinz Rengel.