I am about to make a start on the 1/72 Hasegawa B-25J using the Bombshell Decals for 'Ruthie' of the 489th Bomb Group in Corsica early 1945. The Bombshell decals say 'Ruthie' had neutral grey undersurfaces. But Kitsworld do the same aircraft and they say the undersurafces were natural metal. From what I have read elsewhere the Group practice in late 44 and early 45 seems to have been to paint the upper surfaces of the a/c olive drab and leave the undersurface natural metal so my gut feeling is that Kitsworld is right (though I have seen other models of 'Ruthie' using neutral grey). Before I take the final plunge I wonder if anyone has any comments.
FYI - there is a colour photo here of 'Ruthie's' nose and cockpit section. Looks natural metal to me.
http://www.warwingsart.com/12thAirForce/planes5.html