Check the archives.  There are some great descriptions about the different
features for the model years.  I don't recall how far back they go, I seem to
recal it was around 84 or 85 last time I looked.

The major change was from 85 to 86 when VW went from the 1.9 to 2.1 engine.
 I would recommend purchasing one no older than 86 and the newer the better.

My .02

Gregg Carlen
85 Westy, 76 Goldwing, 51 Plymouth, 75 Mercedes, 69 Alcort...need more toys!