Rockauto- ACDELCO 45F0013 is what I used on my 49 3800. I had to take them to the machine shop to have the bushing honed to fit.
( http://www.rockauto.com/en/catalog/chevrolet,1947,truck,3.5l+217cid+l6,1486576,steering,king+pin+set,7340?a=Referer+www.google.com+URL+%2Fen%2Fcatalog%2Fchevrolet )
