The A-20H was similar to the late-production A-20G, differing mainly by its 1,700 hhp R-2600-29 engine. The A-20K, like the A-20J, featured a glass nose and was derived from the A-20H. Both models were built under the specification DS-460, with a contract (AC-40032) for 825 units, marking the last production run of the A-20 series. Serial numbers for these aircraft ranged from 44-001 to 44-825.
Production of the A-20H/K overlapped with the A-20G/J. The final A-20G was delivered on June 14, 1944, by which time 77 A-20H/Ks had already been completed, with the first delivered to the AAF on February 29. The initial A-20K, serial number 44-009, was delivered on March 24, 1944. Out of the total production, 411 were A-20Hs, and 414 were A-20Ks, though 36 A-20Ks were converted into F-3A photo aircraft.
The distribution of A-20H/K production varied: 140 were sent to Russia under Lend-Lease, 30 A-20Ks to Brazil, and the last 90 units to the RAF. Of the remaining aircraft, around 145 were assigned to US domestic units, 188 to the European theater, and 232 to the Pacific theater.
The last A-20 off the Douglas production line was the A-20K-15-DO, serial number 44-825, nicknamed ‘Caboose.’ Factory workers signed their names on the components during assembly. Despite this tradition, the aircraft was later painted in standard AAF camouflage and RAF markings before being delivered to the AAF on November 1, 1944. It was then transferred to the RAF as Boston V BZ669.