I think you are correct on the early combination wrench. I passed on one a few years ago not realizing how hard they are to find. At least for me anyways.
The M6 is too long
The M8 is listed as an elevating mechanism
The M5 is listed as combination wrench , does not perform allot of functions,
and I dont think it was manufactured that early.
M5 upper left, M8 upper right, M6 lower.
Craig