From my experience, I think Gleaner made 3 different platforms for the K2. The rigid pitman drive type, the floating pitman drive type, and the flex wobble drive box type. The rigid needs no explanation. I believe the floating type was an aftermarket add-on for the pitman drive rigid. The wobble box drive flex platform was fully manufactured by Allis Chalmers. It was introduced for the K2 in about 1978 without the big wide dividers. In either 1979 or 1980 they were introduced with the wide longer dividers. I think these later ones were series 2 flex heads, but not positiveIJ