Tab ..... It is STRANGE

So your going to get a strange idea from me. Are the bellhousing bolts tight....and bolts trans to
bellhousing. You might have a bolt or two that are bottomed out feel tight and are still letting the whole mess move.....ditto flywheel bolts

Do you see where I'm going?

Something IS loose.....and bolts may 'FEEL' tight

I don't think a pilot bush would cause this unless you left it out.Did you leave the bush out?