Here is a soaking suggestion: jack machine up from side with clutch to help penetrant get in. Spray in bolt hole till full, tap for a while, let sit at least half day then turn 1/4 turn and repeat. I have one stuck on a badly rusted max IV that will probably be sliced carefully to remove. Try soaking, careful wedging, and tapping before doing anything drastic.
Don told me this trick and it worked great for me. Remove the t20, suspend the T20 by the clutch with some sort of padding under it, remove the bolt that holds the clutch on, using a large punch and a hammer, tap the input shaft out of the clutch.
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