Hi Gary,
I think I misunderstood your issue because of "Most of my other storage servers are 5.0.3 (one is 5.0.0)".
I was unable to find 5.X Bacula rpms for Fedora 21, just 7.X.
One possibility is to build Bacula from source for this Fedora 21 host.
Also, you could try a post to this list with "5.x rpms for Fedora 21". Maybe someone could create them for you :).
Best regards,
Ana