It was filled with black crud...
We are looking at one more out of a truck that was rolled, and I will likely put a brand new throw-out assembly (slave and bearing) in it to cancel that possible cause of noise once and for all. This brings the price tag up to $450.oo altogether.
The throw-outs are 95 to 99 bucks no matter where you get them.
I've heard these things will run over 500,000 miles if you watch the fluid level, but somebody made a mess out of this truck.
The only bright side here is that I am learning the truck just like the F100, and piece by piece it is becoming right.