I have several taper adapters.
one of them it’s aM2 to M2 adapter which essentially extends the taper.
it is probably about 4”. Aka Morse taper extender.
you will need a drift key to get the taper out of it.
I’ve used it more to extend the spur drive from the headstock when I wanted to drive a blank with a void in.
using this the spur can be close to 6” inside a hole and the blank won’t hit the headstock
hardly ever use it in the tailstock. I don’t even like to extend the ram too much
Does add length to a drill bit with a M2 taper.
lots of machinery places have them. Packard Woodworks or craft suppies should have them