Ok, Seems to be fairly common issue, The plastic barb on the top of your radiator (82-85 I believe) gets brittle with age and breaks off, leaving coolant spraying all over your engine.
Here is a $1.25 fix.
Goto the local hardware store and find one of these barbs. Take the broken piece with you if you can, and maybe even the hose just to make sure you get the right size.
Drill a hole CAREFULLY thats a little smaller than the threaded end of the barb. The tank plastic is very thin and take no effort whatsoever to drill so again, slow and careful. I covered my threads in High temp red gasket sealer to stop any potential leak (might be overkill)
Using pressure from your finger and the correct wrench for the barb, push on it while screwing it against the new drilled hole. IT should thread itself and then tighten up.
Reattach the overflow tank return line, give the gasket sealer a little time to harden and you should be gold.
Nice thing is it's replaceable should it ever break again.