964 side mirror replacement question
 

I have 964 mirrors on my 911 sc and they do not have the mirrors in them, are the 993 mirrors the same size as far as the mirrors go to put in them? or any other mirrors interchangable with them? reason i ask is the 964 mirror are rare and gettin them custom cut is expensive, any ideas ....i do have the replacement ones you get at pepboys and they are crap....let me know thanks