ref. 1832 with the incredible Pellaton caliber 8541ES. This - back then - commercial failure (too heavy, too thick, too expensive) was produced from 1976/77-1984 in only 543 pieces. Cheers, HSTE ...
The "1832" in its name references the first Ingenieur SL (Ref. 1832) from 1976 , which was itself a tribute to the 1955 Ingenieur (Ref. 666) , IWC's first anti-magnetic watch. From the interwebs.
...probably almost unworn kind of MINT contidion. I also had the Ingenieur 866 (with blue sunburst dial and as prototype pilot watch, picture of the latter attached) but sold both of them. Cheers, HSTE ...
That dial is just gorgeous and the overall look and the condition for what is nearly a 50 year old watch is just incredible. Wear and enjoy it in good health. Marc