> Anyone know what year the 600 Arabesque was introduced.
Here's one data point: I have a Shimano "Technical Information" booklet dated "May, 1982" that describes the "Shimano 600EX" derailleurs and shift levers and has photos of the parts. The last sentence of the introduction documents the "arabesque" moniker:
======================================================== High precision, lightness and strength, are all necessary requisites for today's bicycle components. In bringing these together, Shimano has overcome all difficulties associated with the bicycle's drive train by implementation of the "System Components" concept. As a result we are proud to introduce our newest component series -- Shimano 600 EX with many new exciting mechanisms.
The rear derailleur possesses the Hatch-Plate Mechanism which means the chain can be removed easily to simplify necessary maintenance. The front derailleur incorporates the Trap-Ease Mechanism which allows increased ability to shift efficiently, while at the same time reducing noise between the chain and the front derailleur.
To round off the high quality of the 600 EX Series, an artistic arabesque design has been added. ========================================================