Thanks chuckindenver,
You're right, the "C" stocks were mainly issued for the 1903A4, however some did find their way onto 1903A3 NM rifles. I just want to know if anyone knows if SC made "C" stocks. Also, I've provided a link to help explain a type 13 stock. To my knowledge Remington and Smith Corona never made rifle stocks. I think what those folks over at Northridge must have are Keystone, or Springfield made stocks. Maybe Joe and his folks need to to their homework on what they are selling. I'm going to look into it some more and if it turns out they are NOS, I'll get one and post a pic.
http://www.trfindley.com/origstmps/m1903guideb.jpg
http://www.trfindley.com/pgm1903stkid.html