All you need to change the ujoint out is a big C clamp and socket just a little smaller than the ujoint cup. This will allow you to press the old one out. You may have to use some vice grips to get them completely out. Then you can press the new cups back in. OBTW, you're very lucky the driveshaft didn't let go and really tear somthing up. I think you should be looking at this a situation as a "WOW, I was lucky today!"...
. Just my $.02,
. Good luck with the ujoint.