I was doing a 12 Fatboy project and ran in to this issue. There was a change in the tank in 2011 as all softail tanks 12+ have a xxxxx-11 part number. Found a take off (dented) 2012 tank from a Fatboy on eBay.
Thanks for the good information guys. I did some digging in the parts catalogs and it looks like I'm going to need a donor tank for the fuel pump bracket from an 11 or newer to make this idea work. I appreciate your input.