as above nath....buy one thats built already!
my quaife will be available soon as im now running a full dogbox, like skiddus im gonna get danny to check it over prior to any sale.
tbh theres no real need for straight cut box as semi helical gearset is just as good for track stuff and fast road use, but dont think any of these boxes are indestructable as they are not.
i broke third gear on a quaife once and they are meant to be practically indestructable.
some people are running standard boxes and they have lasted ages where as others seem to go through them on a monthly basis, think its down mainly to luck and how much abuse you give them