During 1943 and 1944, 60 B-25s were stripped of their operational equipment and modified to serve as advanced trainers. Conversions were made from B-25D, G, C, and J models, and were redesignated AT-24A, B, C, and D respectively.
In 1948, the AT designation category was eliminated, and the aircraft were again redesignated, this time as TB-25D, TB-25G, TB-25C, and TB-25J respectively. Postwar conversions of the B-25J to TB-25J continued until more than 600 examples had been completed.
Six B-25Js were modified as USAF personnel carriers under the designation VB-25J. Serials were 43-4030, 44-28945, 44-30319, 44-30971, 44-30976, and 45-8891. All the military equipment was removed, the solid nose fairing was fitted, and the fuselage was outfitted with accommodations for passengers. They were assigned to the 1100th Special Air Missions Group at Bolling Field near Washington, D.C. They were later taken over by the 1254th Air Transport Group.