A Vietnam War era olive green steel frame of the M-1952 rucksack. Such a frame has also been used when carrying the PRC 47 radio gear. If you have the above-mentioned classic pack but no frame, get this one immediately. Or use it to build a back-friendly carrying system for firewood or other heavy shit. All you need is Särmä TST Padded Shoulder Straps and enough utility straps or webbing strap and buckles. If you are handy, you can also attach this to some other old packsack.
M-1952 is based on the US WWII Mountain Rucksack and it was favored by Special Forces troops in Vietnam. In addition to the main compartment, it has three smaller pockets on the outside. In case unclear, the frame is positioned with the narrow point upward and the frame hugs you.
These seem to be in very good condition. Then again these are made from steel and they don’t contain anything soft and easily breakable so it is kind of difficult to damage these unless you drive over them with a steam roller.