That's an F-5 forward fuselage, not a T-38 (big differences in the shape of the nose and canopy).
Baugher's serial number list says this:
82-0003 Grumman X-29A (rebuilt F-5A 63-8372)
(reference:
http://home.att.net/~jbaugher/1982.html)
and later lists another here:
65-10573 Northrop F-5A-25-NO -- (N7021) to Norway. Back to USA and cockpit/nose rebuilt as X-29. The fuselage was mated with T-38A 65-10365 to form flying T-38A/F-5A flying under private ownership as N38MX at Fort Wayne IAP, Indiana.
(reference:
http://home.att.net/~jbaugher/1965.html)
So, it looks like the answer is 63-8372 and 65-10573.