How do you change the u-joints in a 1982 chevy pickup?

Our driveline has plastic plugs that are apparently holding the old ujoints in place. Does anyone know how to remove these nasty little buggers? Thanks!!!|||Yes, use a torch heat the jount, melt out the plastic, press out the old one , but in the new one with the clips as supplyed and install it. you are now done.|||Benson has obviously done this before. LOL I too have experienced this. Heating with a torch until the plastic bubbles out is the only way i know.