How old is your existing glass?
It may well be it's covered in tiny pits and scratches.(Normal wear and tear)
Trust me if it is old you will notice it when a new glass is installed next to it.
One can be done but personally if I were replacing one half,I would go the whole nine yards and replace both.
It wouldn't hurt to replace the rubber at the same time either...JMO
Last edited by jockbolter50; 07/08/2011 7:22 AM.