I have a lathe that takes MT-1 spur center and MT-1 live center. Seeing
that I don't know much about lathes, what would happen if I put a MT-2 spur
drive into the MT-1 spindle? Would it fit? Would it fall out? Is there a
visual difference between the MT1 and the MT2? Can they be mistakenly
interchanged? I know they have different taper dimensions but how do you
know what you have without a mic or label?

Thanks.... Just trying to Learn!