If I were you, I would soak it overnight with PB Blaster, insert a large straight edge screw driver tip into the expansion gap of the u-joint, attempt to pry the gap open a little with the screw driver, and slide off the u-joint. If that doesn't work, heat up the u-joint where it connects to the steering wheel column with a MAP gas torch and re-soak the joint after the joint has cooled a little.