47-53 full assembly:
http://www.classicparts.com/1947-53-Parklamp-Assembly-Double-Contact-Clear-Lens/productinfo/47-012/

or, if you just want the 47-59 sockets, etc:
http://www.classicparts.com/1947-59-Double-Contact-Conversion-Kit/productinfo/47-905/

(Try upper-case and lower-case when you type - some people think that all upper-case is like yelling - it doesn't matter to me.)