The best option is to use a long prybar with a chisel-shaped tip, like the straight end of a carpenter's "shepherd's crook" wrecking bar on the flywheel teeth. If it's inconvenient to do it from underneath by removing the sheet metal cover over the lower part of the flywheel, take the starter off and use the pry bar on the ring gear teeth through the starter hole. Be careful not to damage the teeth.

If it's really stuck tight, take the cylinder head off and pour a few ounces of Kroil on top of the pistons.

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It will creep through the rust and puddle in the oil pan. You can drain it out and pour it on the pistons again a few times, if necessary.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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