Sent in by email:
I've been trying to post on your forum to give away a Topolino crownwheel and pinion to a good home. It's been sitting in my garage for forty years or more but your forum seems to be resisting all attempts to be posted to. It was for a pre-war Topo but I suspect it would fit a 500B or 500C and has the car, as opposed to furgoncino, ratio. It can be picked up from Okehampton, Devon.
(My first car was an early 500A - little brakes and quarter-elliptic rear springs - in 1965 and I've since had twenty or more Fiats, currently a Panda 100HP.)