(I'm kind of glad I don't know the width across flats size , but) You do realize it is an octagonal (not hexagonal) "nut" right?
AV-1522? Do a little searching at the old FChat site, here's a good example thread on that topic with some excellent information (and I know there were others): http://www.ferrarichat.com/discus/messages/256120/28133.html
Steve, thanks for the link. I totally forgot to search the old forum. One has to remember if it's a Ferrari related question chances are it's already been asked and discussed on the board. Thnkx again Kenny K.