I have records of three A-26Bs that were converted to XA-26D:
44-34776 factory completed 14 August 1945, accepted and delivered as A-26B 15 March 1946, often reported as another XA-26D prototype. A note on the record states 44-34776 was to be scrapped but was exchanged for 44-35567 which was accepted as an A-26C 28 April, delivered 11 May, to modification centre 8 August, departed the centre 13 September 1945
41-39543, accepted and delivered as A-26B 20 January, redelivered 6 November 1945, Assignment/Project number DOM791D, reported became XA-26D prototype
44-34100, accepted and delivered as A-26B 31 January, redelivered 1 November 1945, Assignment/Project number DOM791D, reported became XA-26D prototyp
The contract for 750 A-26Ds was cancelled after V-J Day. However, the eight-gun nose tested on the XA-26D was later adopted for the B-series and the six-gun wing was adopted for both the B and the C series.