Sticky clutch on a 89 Pete with an Eaton Fuller 13 speed.

I have an 89 Peterbilt with a 3406 Cat motor and a 13 speed. When I depress the clutch I can put the truck into gear without a problem but the pedal is very slow to extend out. I know from my time as an auto mechanic (many years ago!) that more than likely it’s a bad pressure plate. Does the same hold for a truck or are there other possibilities?

 

Thank you for the advice. It’s very much appreciated! I freely admit my lack of knowledge on heavy commercial trucks.That’s why I’m having the work done at a shop but just for my own understanding I wanted to know what else could be wrong beyond what I stated in my OP. What you said makes sense. This truck was a northern truck and it sat for a while before I bought it. Thanks again!!