So you've bought a syncro and realised that there's bugger all by way of documentation and you local VW dealer looks at you like you've just fallen out of the sky when you mention 4wd? Well not to worry - we were all in the same boat about a couple of years ago and hence the existence of this site :-)
We've read and collected quite a bit of info, as well as the phenomenal depth of knowledge contributed by folks like Les Burt, ChrisS and Cullen, from both sides of the (atlantic) pond.
Depending on what you're after try some of the links below:
There's probably more answers in here than anywhere else. New members are welcome, but please do a search on the questions you're asking because someone else has almost certainly joined and asked the exact same questions as you may be doing (no really - "I've just bought a RHD syncro... how do I make it fast" etc - we've all been there - and some of us still are) ;-)
VW Self Study Programmes
These 20-30 page guides known as "SSPs" are like gold dust and are dedicated to specific VW technologies. You can get them off ebay and occasionally find them online if you're lucky or know the right person.
Whilst there's a lot of differences, much of the technology in your syncro is also shared by other VWs - and of course normal engine building/tuning theories apply. There's a selection of books which we've read and rated in some detail. here