Throw out bearing

Interesting. I don't question what you have experienced. It's not the same experience I have had with clutch disc wear. It's possible the wear you experienced is coming from somewhere other than the clutch disc.
...and please understand, I'm not bein smartass in any way shape form or fashion.....just stating what my experience has been. I can remember I was .....probably 19 layin under this truck giving it a service. Greasing, adjusting. Actually there were two of us. It was raining lightly....yeah we were outside. Anyway, Some of the "water" dripping on us didn't look right. I looked at Robert and asked what's up with this rain?" He started laughing his *** off. I said "What?!?!?!" He said you didn't notice what kinda truck this was, did you?" We were workin on a septic tank pump truck. Need I say more? LOL

I will say this about old Gladys...and I'm sure it's a contributing factor. Her linkage is less than stellar. One end of the Z bar had a wallered hole, the other has a half sawed in two pin, so that contributes. Still though, as this clutch wears, the free travel becomes greater. It's always been that way on every old Ford truck I've ever worked on. I've read all stuff that says the opposite, but that's just how these things wear. Something about the z bar and linkage has to be backwards from the norm.