I found the part I needed without difficulty and ordered it from an easily navigated website. It was delivered in a timely fashion.
Shaft - no keyway (hollow) for use w/all
Shaft - no keyway (hollow) for use w/all residential ducted/window and mastercool exception: will not fit marquis units with serial # before "nm" (23 7/8 x 1)
Buy this part and as many parts as you like and pay only $9.99 shipping, within the Contiguous United States.