Rock Auto also has them...both diameters. You can see here:
https://www.rockauto.com/en/catalog/chevrolet,1946,truck,3.5l+217cid+l6,1486452,transmission-manual,clutch+kit,1993
I've done well with LUK parts in the past. They're better than many out there.
The fork snaps on the pivot ball (which unscrews from the bell housing). You can pry it off with a large screwdriver or anything similar. New pivot balls are still sold. I think I bought mine from Rock Auto, actually but that was a few years ago.
