If there is a tang on the end which is common for MT type arbors use for drills, it prevents the arbor from spinning. Although I have not seen a live center tang, because there should minimal or no twisting force. Either the of MT arbor should eject from the tailstock, but the difference is about 1" of travel from the tang. Yes, you loose some of the quill feed, but if it is not an issue than I would leave it or maybe cut the tang by 50%. I just purchased a MT3 ER40 chuck for my tailstock, that did not have a tang, and I just machined one for it. I do not want the MT3 arbor spinning in the tailstock when drilling.