sub-contractors, with the Willow Run plant concentrating on final aircraft assembly. The bugs were eventually worked out of the manufacturing processes, and by 1944, Ford was rolling a Liberator off the Willow Run production line every 63 minutes, 24 hours a day, 7 days a week. At its peak monthly production (August 1944), Willow Run produced 428 B-24s with highest production listed as 100 completed Bombers flying away from Willow Run between April 24 and April 26, 1944. By 1945, Ford produced 70% of the B-24s in two 9-hour shifts. Ford built 6,972 of the 18,482 total B-24s and produced kits for 1,893 more to be assembled by the other manufacturers. The B-24 holds the distinction of being the most produced heavy bomber in history. Army Air Forces support and post-production activities After their manufacture, the next step in the process was the delivery of the aircraft to the operational squadrons. This was done at Willow Run by 1st Concentration Command (1st CC). The 1st CC was responsible for completing the organization and equipment of tactical and combat bombardment squadrons prior to their deployment to the overseas combat theaters. It also provided a final inspection of the aircraft and made any appropriate final changes; i.e., install long-range fuel tanks, remove unnecessary equipment, and give it a final flight safety test. While the planes were being serviced and made ready for overseas movement, personnel for these planes were also being processed. Pilots, co-pilots, navigators and crew chiefs were assigned as a crew for each aircraft, sleeping on 1,300 cots as they waited for the B-24s to roll off the assembly line. Paperwork was handled, necessary specific B-24 life support equipment was issued and some technical training for supporting the aircraft accomplished. Once production began, it became difficult to introduce changes dictated by field experience in the various overseas theaters onto the production line in a timely fashion. Consequently, newly constructed Liberators needed modifications for the specific geographic areas they were to be flown in combat. For this reason, a series of Air Technical Service Command modification centers were established for the incorporation of these required theater changes into new Liberators following their manufacture and assignments. There were seven known modification centers: the Birmingham Air Depot in Alabama; Consolidated's Fort Worth plant, the Oklahoma City Air Materiel Center at Tinker Field, the Tucson Modification Center at Tucson International Airport; the Northwest Airlines