i did this on my jetta i used the cluster out of a cabriolet, works beautifully. follow the conversion in the faq. if you can solder this job can easily be done by you
The opto sensor circuit I made from the 4crawler schematics worked fine plugged into a test tach. Looks like the tach in my Scirocco that worked fine 2 years ago is the problem. I love VW wiring and electronics.