Do the blades counter-rotate?
If so, that makes a difference on which side the blade goes on the spindle.
(The right blade goes clockwise while the left blade goes counter clockwise.)
Any help would be appreciated.
Only on mowers that have a rear discharge.
And fairly well obviously yes the blades the blades have a direction.
ON most mowers with a counter rotating shaft the left hand cut blade has a different mount so you can not put them on the wrong spindles.
OTOH you can put any blade on upside down and despite the fact that man are marked "GRASS SIDE" I generally get 1 or 2 callouts a ear to find blades on upside down, particularly mulching blades.