http://www.stevenmatarazzo.com/oldmac/AppleGuides/Macintosh_CPUs_and_Expansion_Cards/Macintosh_IIfx_Logic_Board_Upgrade.pdf

This.

Doesn't look like you get a badge, which would explain the Mac II that I have that has a IIfx board.  Came from a stash not used since the 90's, so I'm thinking it would have been a genuine upgrade.