95 C2500 Clutch problem

My truck has some clutch problems. The pedal is sometimes very hard to push, only disengaging at the very bottom of pedal travel. Other times the
pressure is normal. I have checked the fluid level and it is not going down. I suspected a faulty slave cylinder and replaced it. The problem is better, but not fixed. Can it be anything other than the master cylinder? This is not an air problem, I know what that feels like and how it affects shifting.
Any thoughts? Should I just replace the master cylinder? Thanks,
Rick rwbaker1 at this domain swbell.net
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
Add image file

Motorsforum.com is a website by car enthusiasts for car enthusiasts. It is not affiliated with any of the car or spare part manufacturers or car dealers discussed here. All logos and trade names are the property of their respective owners.