Even though I'm just about all Chevy/GM, I do have a Ford Wrecker that I use as a yard truck (It was too good a deal to pass up, lol). If I let it sit too long the Clutch will stick. And it really sticks. I have to crawl under and break it loose as Jerry has described above. What I end up doing is put a wooden stick from the Clutch Pedal to the Seat to prevent it from happening.
By the way, anyone who wants to trade for a Chevy Wrecker, just let me know, lol.