I've been trying to free up a stuck 216 and I'm not having much luck. It sat for 20+ years in a barn. I've been filling up the plug holes with ATF and Acetone for the past few weeks and I haven't had any luck getting the engine to even wiggle.
Have you considered that you may have a stuck clutch? Maybe it's time to pull the truck with a tractor or another truck, that's worked for me!
