The source was US National archives - collection RG457 - Entry 9032 - box 1.367 - NR 4263.
There is an interesting report in that file concerning the German exploitation of the US M-209 cipher machine in late 1944 and early 1945:
NA 7 Sigint HQ was the Signal Intelligence Evaluation Center of KONA 7 (Kommandeur der Nachrichtenaufklärung - Signals Intelligence Regiment) covering Italy.
According to TICOM report IF-272 only two reports of KONA 7 survived WWII. These were E-Bericht IV/44 and E-Bericht I/45.
Unfortunately I don’t know where to find them.