I performed this job recently separating my G50 gearbox from the engine. Tried all the suggested techniques to no avail (penetrating oil, slide hammer, etc).
I rigged up a length of screwed rod and a 'strongback' to apply tension to the shaft. This didn't work. However application of heat to the bearing areas with tension still applied did work. I borrowed oxy/acetylene, but I think propane or Mapp gas would have worked. Whilst applying gentle heat I could hear a few 'pinging' noises as the rod released - slowly at first for the first few thou, applied more tension, more heat, and out it came. I think it was jammed in the bearing closest to the point of pull.
Stongback and rod bottom left of 1st picture.
