OK so we have established that this is an old 13 speed? I am pretty certain that this is not the original gear shifter, back in the early eighties the range shifter was the old style, attached to the stick and not incorporated into the gear knob. Some of the deep reduction trucks even had the deep shifter on the dash and only the low to high shifter on the gear stick. So we can assume that this gear shifter was taken
Discuss this in the forum topic Road ranger question, trouble changing from high range to low range.