I've a copy of Martin Streetly's book 'The Aircraft of 100 Group' (ISBN 0 7090 1043 5, published in 1984) on the shelf. In the chapter on the B24 he notes that USAAF did operate two squadrons of B24's in the Carpet Bagger role. These were the 857 and 858 Bombardment squadrons. They were used in the jamming and ELINT roles, alongside 100 Group. As they had a close relationship with 100 Group, they were known to have visited their RAF counterparts at RAF Oulton in Norfolk.
The RAF versions had the nose turret disarmed and covered in doped fabric. Photos of USAAF B24's show the gazed nose, similar the B24D's on J model Liberators.
Hope this helps a bit.