OK- - - -next attempt- - - - -take the sheet metal cover off the bottom of the flywheel if you haven't removed it already to drop the oil pan, and use a short pry bar between the flywheel ring gear teeth and the edge of the bellhousing to see if you can move the engine that way. Also look for discolored connecting rods of main bearing caps which might indicate a bearing had gotten hot and seized up. If you can't budge the engine in either direction with a pry bar on the flywheel, there's definitely something serious going on. Start loosening the main bearing cap bolts a turn or more and see if the crankshaft frees up. If not, loosen up any of the connecting rods you can reach. Eventually you'll find the tight spot.
Jerry
