I'd suggest pulling the flywheel as long as you're into things this deeply. I seem to remember there's a freeze plug at the back of the block that might have been pushed out against the flywheel from a freeze-up? The flywheel removal only involves 6 bolts, and it's really not all that heavy, but wear a pair of leather gloves to prevent the ring gear teeth from digging into your hands as you lower it out of the bellhousing. Once the flywheel is removed, you can put 2 or 3 bolts back into the crankshaft hub and use a pry bar to turn the crankshaft. If it still makes noise with the flywheel removed, the noise just about has to be internal. Good luck!
Jerry
