I'm a little confused on this part

"This means, you must replace the factory 5.3L flex plate with a flex plate and spacer from any 2002+ ¾ HD GM truck that originally came with a 4L80e transmission."

I thought as long as the flexplate is off a chevy, and has 6 torque converter bolts, it will work????????? I plan on using a flexplate off a 1998, but after reading this I am worried I might have to find another flexplate