Thanks Trev!
You are right, the guard of my '55 SS is longer and there is no gap at the front (and no fixing hole on the inner primary casing, plus the fixings on the swing arm are different, wich were changed with the introduction of the fecg in 56).
I was wondering about the gap on the A10 and the hole in the inner primary, but actually didn't care too much about it (the gap is hidden by the tyre pump)
It makes sense to have that front part fitted if you want to upgrade your bike with the fecg, would be much less work. Maybe that was the idea behind it, who knows.
So I'd better keep it. There didn't seem to be too much interest anyway...
Cheers, Markus