If your talking on the bottom of the aircraft, the aft 1/2 is removeable, hard to see with these pictures. 4 bolts torqued at 100 inch lbs, 2 at 350 and 2 more at 750. There are panels for access to the gearbox that drives the generators and hydo pumps.
EDIT: even though this is a T-38, same frame. See the line just before the stabs going toward the rudder, taht is the part removed to get the engines out.
http://clipart-finder.com/clipart/t-38-talon.html
Hope the link works
Kevin