Sorry to resurrect this old thread, but for posterities sake, I acquired a VSL late last year and found that it was neither a MT 4 1/2 or MT 5. Instead, it is a short Jarno #13 Taper. There is a seller on Ebay that has Jarno 13 dead centers, which I bought and cut some off of the narrow end - it fits my VSL perfectly.
I have seen others claim that MT 4 1/2 or 5's fit as well, so perhaps there are different versions of the VSL spindle out there.