i had this problem when i tore down my 360 in my old truck. the best bet it soak it in PB blaster to start with. if ppossible, wrap a string around it and soak the string in PB blaster. if its flushly broken,you'll hafta get an easy out or broken screw extractor.
'90 YJ, ford 8.8, SOA, lincoln front, aussie rear, 4.88s, swampers.