I don't know, I assume the bolts should point upwards through the mudguard, that's how I have always fitted mine, but because I use longer bolts with a good sized rubber spacer the rounded profile of the mudguard always seems to splay the ends of the bolts out a bit to far and makes fitting the regulator difficult.
It could be that 4 of the (6) thin washers go each side of the (2)rubber washer?
But there are three nuts on each bolt and I'm not sure of the correct order below the regulator?