Unfortunately there was never a manual transmission in the H-Body Bonneville [87-current].
As far as a flywheel and clutch for sale from GM... I don't know. By your sig, you seem to not be retarded when it comes to cars. Manual or automatic, both have flywheels. Don't quote me on this, but I really doubt automatic tranny flywheels are the same as manual tranny flywheels. As far as a clutch, the only thing that could explain that was a TCC Clutch, or one of the internal clutches.
Do you happen to have a link to some of these items? May be able to figure out what'* up with it, if you'd like