Certain modifications had to be made to the B-25Bs to make them suitable for the mission. Since the raid was going to be made at low level, the retractable ventral turret was removed, saving about 600 pounds of weight. More fuel was added to the plane, bringing the total fuel load to 1141 gallons--646 gallons in the wing tanks, 225 gallons in the bomb bay tank, 160 gallons in a collapsable tank carried in the crawlspace above the bomb bay, 160 gallons in the ventral turret space, and ten 5-gallon cans for refills. The still-secret Norden bombsight was removed, lest it fall into Japanese hands. It was replaced by a makeshift bombsight that proved more satisfactory for low level operations. The bomb load consisted of four 500-pound bombs. As a deterrent against Japanese fighters making stern attacks, a pair of dummy guns in the form of wooden sticks painted black were attached to the extreme rear fuselage, protruding out the back of the transparent tail cap. Takeoff weight was about 31,000 pounds.