The bolt pattern for the LS1 torque converter is different than a standard bolt pattern. I could not use the flex plate from a 2002 V8 van that had a 4L60E. I guess they use the stardard turbo 400/350 bolt pattern along with the 4L80E. The flex plate will not clear the back of the block without a spacer unless they make a flywheel specifically for a LS1 type engine to 4L80E.