Dubey & Schaldenbrand age determination by year of manufacture chronographs

The years of manufacture listed below, by model and caliber, allow at least a rough age determination of Dubey&Schaldenbrand watches/chronographs:

1950 Valjoux Cal 92, 17 jewels stainless steel

1993 Valjoux Cal 7751, automatic, stainless steel, full calendar and moon phase

1993 Valjoux Cal 7751 gold-plated, full calendar and moon phase

1993 Valjoux Kal 7750, military design, hard chrome-plated metal

1994 Eta Cal 7750, 17 jewels, automatic, stainless steel

Source: Wolfgang Salm "Wristwatches"