In 1982 I made a "freeze" plug beside the road for my '68 Bronco on the way from Florida to California. I was cruising along down a long slope when I was surprised by a cloud of steam from under the hood. When I figured out what had happened, I walked back and looked for the plug. I didn't find it but I found a chunk of rubber, whittled it into a disc, punched a hole in the middle, and installed a bolt, nut, and two washers; I tethered it with a string just in case, and plugged the hole. This repair lasted for years. Steve