Thanks Brian,
Now I remember where it came from. After I discovered the broken original, I had just about given up finding a reasonable priced replacement part. I met an Iranian machinist who had immigrated to the US in the 80's. He owned a small machine shop specializing in custom small orders, hard to get gun parts, etc. He said he was once an armorer in the Iranian Army. After the US and Iran broke off relations they were forced to make all the replacement parts for their US supplied arms. He made several of them for me overnight :-).
JeffL