The reason i picked the VW knobs is that the thread inside the knob goes all the way to the top. That way, you just buy the knobs, screw them on, measure where a flush point would be and cut the bottom off. Even after cutting the bottom of the knob off, it will still thread and fit in the hole. I cut about a quarter of an inch off of them to fit on my car. Hope that helps.
Slick