1995 Chevy Tahoe

The transmissions' weight should never be placed on the pan. It sounds like you are going to just that -- not a good idea. You should use a transmission jack and remove it completely.
The u-joints should be pressed out -- a good vice will work, but you may have to apply heat to the cups. The factory uses a plastic mold to retain the u-joint cups, it is this plastic "ring" that must be broken in order to remove the u-joint -- applying heat melts this ring and makes it easier.