By shaft, do you mean 'quill', ie there is an aluminium wedge thet is pulled upwards to secure the stem by tightening a 6mm bolt at the top of the quill? These days, a 'normal' stem would be an 'aheadset' type where the unthreaded steerer tube protrudes up through the aheadset and the stem is basically a tube with opposing clamps on either end, one of which clamps the handlebar and the other the the unthreaded steerer tube ?