With 120,000+ miles on the old 1988 I-6, the clutch just barely disengages when the pedal is on the floor. With a hydraulic clutch linkage, is this an indication that my disc is getting thin ??? Fluid level is full up, and the firewall panel holding the master cylinder has been bolted together (since separating years ago). Would have expected the slave cylinder to self adjust - but don't know. Clutch is original.

 

your Hydro clutch linkage is indeed self adjusting. there is a small spring in the slave cylinder to keep the plunger pushing on the clutch fork. so when the disc wears it keeps taking up the slack that would otherwise occur in a mechanical linkage. odds are it is not activating the correct distance. Your Hydro-clutch linkage is probably wearing out. the seals get old and start to let fluid by. good luck.
Eric

Proud owner of a '73 F-250 4x4 High Boy, 460 V8, NP435, NP205
And a '68 Bronco 289 v8 , NP435 , Dana 20