Those spacers aren't really anything special- 1/2" long 3/8" ID x 5/8" or 3/4" OD heavy wall steel bushings/spacers from your local ACE or similar good hardware store will work. The original spacers are like 0.469" tall or something like that. 0.5" will be close enough as long as you get four new ones.
24302 should be a series II. There should be provision for an oil filter (blockoff plate held on with a couple of allen head bolts forward of the RH cylinder). If that is there it is a series II. Also, if the oil fill cap is a plastic cap and not a pipe plug, it is probably a series II.
Hydraulic lift control valve should be easy to free up. Squirt some Kroil or PB blaster into the part that moves, and try tapping it back and forth with a hammer. Eventually it should move. Problem is likely dry O-rings that seal the unit.
Tractor has obviously been repainted. Serial number is below 719,999 but tractor was originally yellow based on the paint chip next to the data tag, so it will have mostly IH parts but be assembled by MTD. Who knows what a previous owner did with decals based on the paint job, but I have also seen some goofy things with decals in that transition period before MTD was fully producing all of the parts. T