I was thinking maybe there is a morse taper there, but was not sure, and it did not appear to be the case - I remember the chuck (with B16 mounting hole) was packed separately, and it was easy to remove it from spindle after couple of years use.
I will try again and have a better look...
If so, this would make my life much easier...
Hmmm.. it seems
some models have MT2 taper after all.