Swans neck micro regulator on Cal 89?

I'd really appreciate some help with this.
A friend has just inherited a lovely gold cased Cal 89, and I showed him round it. I'm not familiar with IWC, but the Cal 89 has a strong reputation. I thought I'd do a little digging to give him some history.
The movement number is 1406443 and the case is 1437675. I know the crown is not right, and am on the hunt for a suitable replacement.
However one thing that sticks out is the movement has a very nice micro-regulator that for all my googling, I cannot see another example of, might it be a Swan's neck regulator?). It has an additional spring to push the regulator one way, and a small adjustment screw in the plane of the mainplate to push it the other. Was this an optional extra, or an aftermarket enhancement?

Another question, the dial shows International Watch Schaffhausen, missing the "Co" Is this again an anomaly for watches fromthe 1950s?

Many thanks,
Max

Max

Hi Pulsfoursmax,

the watch movement you are referring to is not a Calibre 89 but a Calibre 401. The 89 is 26.5mm ( 12 lignes)in diameter and 4.25mm in height an ticks with 18000 amplitudes per hour, whereas the 401 is 23.4mm (10 lignes) in diameter and 3.7 mm in height with alitle increased 19800 ampl/h. Cal 89 was made from 1946 to 1976 Cal. 401 1952 to 1965. The total production numers of Cal 89 was 223800 and Cal 401 26400 pcs.

The dial of the watch you show is unfortunately reprinted.

br

Cromagnonman

Hi Puslfoursmax,

the movement number leads to a year of production in1957. The case was produced in 1958. This reference can shows up in the market quite somethimes, however mostly the steel version and not the 18ct gold one.

- Cromagnonman

ShaffNausen