wait... you'll be using an LS6 flywheel, correct? i thought you were wanting to reuse your old one, but even then - you have a 4.3, not a 4.8

what i do know is that you can't use an LS1 flywheel with a 4.8/5.3, but that's an issue of bolting to the crank. i have no clue whether or not an LS6 flywheel will mate to this transmission... but it will easily go with a t-56, which is what you'll be probably be looking for in the future.