M-1956 Buttpack Adapter Straps - FIELD & PERSONAL GEAR SECTION

Hey gang, Hopefully a real simple question, and it's exactly as the title states. When were the M-1956 buttpack adapter straps first used/issued in Nam. I couldn't find much out there on either the forum or the "Net" in general, so I figured I'd post the question here and see what the field gear

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