This is the rare Heuer ref. 980.004/1. With original full length bracelet. This bracelet was not signed on clasp. A large 40mm rarely seen Heuer.
It's from the 1980's and have the new slimmer ETA 955.114 movement. The same movement used in the updated TagHeuer 1000 diver series with a N behind the referance number.
I like the black Date/Day window, that's a nice detail.
It was shown in the 1982 Heuer diver watch catalogue. My watch moved to a new owner as I found the design a little to simple.
German watchmaker Sinn made their own version with an automtic movement.