And to answer Dux, IIRC, the number 5 plane does have the number painted upside down.  At least on one side of the inlet. 
I'll dig through my photo albums and see if I can find a pic of #5 on the ground/flying level.
[Edit: I found 
this pic online.  You can clearly see the upside down 5]
There are some great pics on that site.  Looks like the 5 on the other side is right side up... 

Cheers, 
Spitter