I have an 86 auto trans that I purchased. It ran at the time, but I started to change the tub out, which ended up taking a year. Now, the starter engages but the engine won't turn over, load clunk! I even jumped the starter straight from the battery, same thing. Could the auto tranny cause the flywheel to lock and not turn? What could cause an engine not to turn over? Need a checklist of causes, excluding the starter itself, I know it's good, bought a brand new one to eliminate that possibility. Help!