If it was an Alouette III it probably had an Artouste IIIB engine, the big brother of the Astazou. It is a fixed shaft engine with a centrifugal clutch mounted on the drive shaft connecting the engine and transmission. There are two different clutches, the standard and the unified. The major difference to the pilot was the engagement rpm.
The clutch system worked well IF the pilot used proper technique. Both clutches had a 10 second window for proper engagement. Faster than 35 seconds and you were using too much of the clutch shortening it's life. Longer than 45 seconds glazed the clutch.
The clutch is a frequent source of high frequency vibrations.
Great helicopters and great engines if you don't mind the high fuel consumption and noise.