OK, I don't believe it was the 90' NA motor that was different. I believe that may be the same as whats on Wood75's motor but I can't find my 90' NA lower cover at the moment. I'm not sure of the year of the motor I just took a picture of but I think it's a 95. Just trying to get an idea of the exact year they changed it. The 93' (which you can't tell by the pictures because of the crank pully in the way) also had an open area like Woody75's.
And some pics of the 93' motor I'm getting ready to put in my 90' NA.