I've done the same thing with JB weld, but mine has started dribbling again already after two years. But the truck is driveable, so what the heck. Search the site here for JB weld you will find some good tips. When I did mine, after draining the block I even hooked my shop-vac up to the radiator while applying the JB weld, it sucked right into the crack. Not that it helped in the long run.
Some other guys here will mention different welding patches. Do a search and you'll find both positive and negative opinions.
Whatever you do, drill small holes at the end of your crack before you patch it, to keep the crack from spreading.
