OK are you saying when you "give up" on depressing the pedal you can only get it down so far, and there's 6" left between the pedal and floor?
Some generalities:
IF the above is true certainly is not right. Start by opening a bleeder and see if the pedal goes on down freely. This will tell you if there is a mechanical bind problem in the master/ pedal/ mount/ pushrod setup
If that allows the pedal to depress fully, then:
1.....Slave/ master might be so mismatched that slave is running out of travel
2....Might be clutch fork/ throwout bearing is bent/ broken/ off the fork pivot/ pivot broke, etc
3...Does not appear to me that slave is moving far enough. You might have a situation IE example "junk" rust in the slave or NOT ENOUGH travel in the slave to start with, the slave might be "part way" extended when you THINK it is all the way retracted.
Only way I know to approach that is to:
Remove slave, measure bore, try to find out what size bore the truck CAME with (if this is original type master)
Take slave apart make sure it's clean and that piston has full travel of slave bore.
Try to get flashlight/ mirror/ camera/ etc and wiggle the fork around and inspect. Try to determine if fork pivot is loose / broken or even present and if TO bearing / fork seem free etc
Saying "know it is hard to depress" is somewhat subjective. That clutch might be "firm" but if you've driven a 1/2 or 3/4 T "stick" pickup it should not necessarily be any tougher to operate
