Where do I find SM318 pilot thrust washers

[ayetav]

Hey all,

I inherited my great grandpa's 66' C10 Stepside. I was going through and replacing all bearings seals on engine/trans which is the original 230ci and Muncie 318 trans. I have just about everything on the trans put back together, but I can't seem to find my original thrust washers and they aren't included in small parts kits or rebuild kits that I can find.

Does anyone have idea where I can find two thrust washers? Parts 11 and 12 from attached part diagram