Bean's supplies one with their fuel system for the OBS. Its a custom made out of a fuel rail plug and the tit off of a steel AN-6 male fitting . The hose fitting is a close sweep 90* AN-6 female to An-6 hose fitting. Aeroquip makes a close 90*sweep bend, the wide sweep 90*s don't clear the firewall and the cast 90* isn't smooth.
My buddy made up some for me by cutting off the AN-6 male, brazing it to the fuel rail plug head end and boring out the 3/8" hole through the works on a lathe. I like to use a steel sweep 90* since I tend to bend up the aluminum hose fittings in tight spots.
DI used to sell these fittings for about $20 each.