They are out 3/8 of a inch. I found a Ford service tip on the problem. I must not be the only one breaking flexplates !!
3/8" out of the spacer is OK...3/8" out of the block (not all the way through the spacer) would be a major problem.
time to get out a straight edge, a set of feeler gauges...and start looking for things that aren't flat between the back of the engine block, (uniform) thickness of the aluminum horseshoe spacer...(uniform) thickness of the thick flexplate adapter...tight bolts (on thick flexplate adapter & bellhousing)?
next will be that of the trans bellhousing mating surface is flat (straight edge)...and no cracks around bellhousing
converter face flat? (again, straight edge it)
loose converter bolts/nuts?
input shaft on trans tight (no side to side play)?
check driveshaft for being bent, check cardan joint on upper end of driveshaft (been there...) ...
the OEM flexplate isn't usually
the cause of a flexplate failure.