I felt that with the TiiCo kit going in my van, I needed a tach that could see the full RPM range of my new motor. The answer was to get a 7k RPM tach out of a Golf/Jetta II dash cluster. As I found out, it was much easier than I thought it was going to be to install the higher RPM tach in my van. 

Once you remove the instrument cluster from the van, you'll have to remove the 2 pods (speedo and tach) and the center section from the housing. The blue circuit board will come with it. When that is done, you'll be able to see the faces of the gauges without the clear plastic in the way. Pop the tach needle off the gauge (I used a pair of butter knives, one under each side of the center of the gauge needle), and remove the 2 small screws that hold the tach face in place. 

Next you'll have to look at the back of the pod and remove the 5 nuts that hold the H2O temp and fuel gauges on. After that, you will be able to see the tach itself sitting in the center of the pod. there are 2 screws that go in from the back to hold the tach in place. If you remove these screws, the tach will pull right out. Simply dismember a Golf/Jetta II cluster (very similar dismantling method) and remove its tach and screw it into the Vanagon cluster.

There are 2 ways to have the 7k tach face visible. The quick and easy way is to just use the tach face from the Golf/Jetta cluster. The only problem with that is that the golf/Jetta has a flat spot at the bottom of the gauge, so there will be a slight gap at the bottom once it's in the V'gon cluster.

The other way is to put a 7k RPM overlay on the V'gon tach face (as well as the speedo and dummy light indicators). An explanation of that is also on this site.