I'd like to replace the spindle and blade holder on my Series 4 but the usual sources (PartsTree.com and one other I can't remember right now) don't seem to have them listed. They DO have the parts listed for newer models in the same size range I have, and I'd like to see if someone here knows if they will work out OK. E-bay sellers have them listed for "Most snapper rear engine riding mowers," so I'm inclined that the spindle and blade holder will work on mine. The part numbers listed for the newer models are below.
I happened to just get some spindles and other stuff that I ordered as an experiment to see what fits and sure enough, the part numbers I have listed above both match my old take off parts:
Spindle PN: 7200147YP
Holder PN: 7037751BMYP
Just finished installed them today, actually, after finding I was missing some other hardware.
So there ya go. New parts will fit on an old mower, at least to some extent.