The B-25D and J will have a bomb bay tank on missions 8 zones or longer. Also, in the B-25 expansion you will have MP-8, Bomb Load (Optional). MP-8 is a very short version of "Bomb Loads." On longer missions your bomb load will be smaller, 4 bombs maximum.
MP-8 will also make it possible to have bombs on wing racks.
B-25C will not have a tank only 4 bombs on longer missions.