I use SYR, and they are excellent about answering questions like that promptly. Whatever shipping label provider you're using should do the same.
SYR advises (demands, kind of) that FedEx not be contacted directly, in large part because when we civilians ship reptiles, we're not actually contracting with FedEx -- we are contracting with SYR (or equivalent provider) who in turn contracts with FedEx. Regular Joes and Janes can't ship live animals via FedEx -- we have to ride on another company's arrangement for doing so.