Crank spacer????????
or
6.0 (4l80e) flexplate with spacer between crank and flexplate (as it's flat) and holes should line up for th350/th400 converter, they did in my case.
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If you had a 5.3L curved flex plate never used the spacer in stock form.
So if you buy a used flat one it should have a spacer already, Now if you buy new I am not sure if the spacer comes with it as I have always just ran a used one.
Notethe one on the right with the shorter crank bolts is the curved 5.3L one. The flat flex plate is on the left note the longer bolts and spacer.
0222101754-00.jpg?t=1266884737
Stock 6.0L 4l80 flex plate and spacer. This is the crank side.
0222101755-01.jpg?t=1266884768
Dished flex plate with GM spacer after the crank.

Spacer from local dealer (cheaper online BTW)
GM PART # 12563532
CATEGORY: Engine Flywheel
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $52.86
BOLTS
GM PART # 12563533
CATEGORY: All
PACK QTY: 1
CORE CHARGE: $0.00
GM LIST: $6.86
as for the spacer comming off with the flywheel, never seen that happen.
spacer is always stuck to the crank. ive taken off several. probably at least 5.




