You seperate it where the black plastic connects to the metal shaft in the previous pic. Heat the shaft with the torch some and grab the upper part with vice grips and pull.
-- The B&M shift knob I put on uses a plasitc sleeve that I pounded onto the bare rod and then screwed the new shifter onto it. I recomend getting a new little plastic piece at the bottom of the pivot on the previous pic and also the green "truck" gasket that the larger half circle (with the spring above it) glides on. -- Hope that makes sense--
Also for the 2 rubber boots, use a hose clamp to tighten them onto the now smaller bare metal shaft.
My Shortened one: