Wow, old post!
ISA stands for Institut de Sélection Animale, who developed them. Hubbard is another company that developed a sex link cross.
As far as I know there is no way to tell what exactly they used to make the specific crosses. My guess is the strains of chicken they use don't really...
The male has to me the red/gold one, doesn't work the other way around.
But there's more!
The gold to silver cross. Mating a gold male such as Rhode Island Red, Buff Rock, Buff Leghorn, Buff Orpington, Red or Buff Sussex to silver hens such as Light Sussex, Light Brahma or pure White...