Didn't know that there were two designs. The only N20 I've seen in person is Dave Spain's boat, which I think is fairly old.
There are actually three different I20 rudders:
The original "pin head"
The "butterknife" (which came on boats for only three or four months - but was common on '04 and '05 F18s)
The "spade" - current fat, clover leaf looking rudder blade.
