What brand PTO shaft? Manufacturers (i.e. Bush Hog, Woods, KK, ect) use "generic" shafts made by several companies. Example....My KK tiller has a Eurocardan shaft and slip clutch. Look for a name and post back. I've got a few ideas on where to look depending on the name you find.
That's on a Howse mower but the shield is clearly generic.
What's driving me nuts is I saw a tray of those screws in a farm-type store somewhere. Maybe it was when I went east to Omaha for a wedding and stopped by a TSC there. I should have bought a handfull when I saw them.
RK 55HC,ym1700, NH7610S, Ford 8N, 2N, NAA, 660, 850 x2, 541, 950, 941D, 951, 2000, 3000, 4000, 4600, 5000, 740, IH 'C' 'H', CUB, John Deere 'B', allis 'G', case VAC
i doubt you will find them as a component part without buying the plastic shield. I know neither mower manual I have, which DOES have a shield and shaft brakdown, though does not list them seperately.