1965 Dodge Dart Speedometer

You might want to call these guys. OE-Style Speedometer Cable for 1960-1965 MoPar A-Body I have bought these cables from them because i have 2 65 Darts. They are very helpful.
how would you go about removing the cable? Ive gotten under my 65 dart and and found where the cable goes into the transmission, I can also see a small metal hook held on by a nut. After removing the hook, the cable does not want to come out. Is there something else I need to do in order to remove it? I don't want to pull too hard in fear of breaking the cable or something within the transmission. It seems to be stuck in there and has no play room.