Quaife or plate diff they still use the original cwp which IS a weak link.

Either go 9" or as your saying find something thats more suitable from another car.

Some people don't break the 7.5" units, I guess thats as their either not that hard on their car or its not making the power they thought.

I've only known one person personally with a genuine 500+hp engine in a Saph and that would smash ANY Cosworth diff you put in it with the way he drove it, a 9" was the only solution for him but that doesn't mean there aren't cheaper options available