Could you share where do we find such info?
in the documentation file from Belsimtek there´s no specification of which exact version of the "E" we have, but as you mentioned the curved fin, I assume they were developped as the USAF F5-E Agressor, without the refueling probe.
Nevertheless, even the F-5A operated by Canada and later by Venezuela were fitted with the air refueling probe, and the F-5 was built with a certain level of modularity. In a brief research it seems like several export versions were fitted with this feature;
Canada / Venezuela / Botswana (F-5As)
Brazil
Chile
Morocco
Saudi Arabia (F-5Es with agressor-styled fin)
Singapore (Also agressor style, but known to have being extensively upgraded)
Tunisia
Important to notice that some F-5 operated by the USAF had it, but fitted to the left side of the fuselage:
http://thempirestwilight.wikia.com/wiki/F-5_Freedom_Fighter
Just think it would be a nice addition to the already nice product offered by Belsimtek, without being unrealistic/unnacurated. :)