The Centaur was launched in 1989 as a lower cost alternative to the 1988 Campagnolo Euclid. As far as I can tell the only difference was that the inner parallelogram plate was a steel pressing - which was presumably marginally cheaper than the Euclid's aluminium forging.

I believe that this is a second generation Campagnolo Centaur from 1990 - with a cable adjuster.

Some relevant details are:

• There is a spring adjuster on the p-pivot.
• The cable adjuster is round and threads straight into the aluminium of the b-pivot.
• It has a single parallelogram spring using ~2.0mm wire.
• The inner parallelogram plate is a steel pressing.
• The cable clamp nut is a smooth Allen key item.
• The pulley wheels are a conventional ball-bearingless design in black.
• The inner pulley cage plate is steel and has a spoke deflector.

• Derailleur brands: Campagnolo
• Categories: Campagnolo - mountain bike madness
• Country: Italy
• Date of introduction: 1990
• Date of this example: unknown
• Model no.: Q010-SM
• Weight: 296g
• Maximum cog: 30 teeth (Campagnolo)
• Total capacity: 32 teeth (Campagnolo)
• Pulley centre to centre: 53mm
• Index compatibility: 8 speed
• Chain width: 3/32
• Logic: top normal
• B pivot: sprung
• P pivot: sprung
• Materials: largely aluminium with a steel inner parallelogram plate and inner pulley cage plate