Hi Ed
Unlikely it cannot be the linkage, I have Tilton hydraulic underfloor pedals and the new Tilton 6000 perfect adjusted.
The LS6 did not run for nearby 10 years, so the very loud squeaking will be from the dry spot, as you say.
If I run the engine for minutes, the squeaking becomes quieter until it is gone.
But every time I start the engine again, the squeaking is the same. Temperature?
Hopefully during riding it will fix on its one
Still thinking of giving some WD40 shots inside the bell housing ?
the Tilton 6000 will ignore it, my concern is that the clutch will then slip