Re: Do i need this spacer ?
That is called a "Flare Washer" Or "Anti-cavitation Washer." A spacer of some sort is needed otherwise the prop will slide back and forth on the shaft. It does not matter that the splines have been stripped from the plastic flare washer. It will work just as well.
If you have the flare washer, you most likely have the extended prop shaft which was designed for a tailcone. If you do not have the tailcone, simply slip a large cotter pin in the hole and it will prevent the prop nut from backing off all the way, so you don't need to worry
As you can see from the photos, it is not absolutely necessary to use a tailcone but most props will require some sort of spacer. It need not be the plastic flare washer, it can be a special spacer made for these shafts or even a large plain stainless steel washer or two.
