i have an 08 supercrew with an open diff.
i was thinking of getting a factory ford L/S diff but replacing the stock clutch plates with carbon fiber plates from the mustang cobra. will they perform any better or last any longer than the stock plates? or should i just go with a better brand L/S?

 

If I were you i would look into a detroit true trac. It is a gear design that doesn't wear out I have been using it in my 04 for about a year in a half and have seen no problems. It is quiet and always there when i need it. It also will lock up insted of slip like cluch plates in extreme situations. I wanted to go your way first then I saw the true trac. Just do a search im sure you will find alot of info.
Good luck