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New to my 1941 GMC 3/4 ton. 228 w/ 4-speed. I've never had an old manual trans vehicle before. The truck has sat for about two years and before that was driven about 5-10 times per year. It was parked because it wouldn't start. The clutch worked fine at that point I'm told. I got it running easy enough, but the clutch is stuck engaged and won't shift into any gears. also, with the pedal depressed, and in gear, if i bump the starter the truck lurches. it runs fine in neutral. i removed the lower clutch cover and adjusted the play in the pedal to spec (it's almost at the end of the adjuster). the pressure plate moves when the clutch is depressed... I can see the "square" tab on the PP move in it's slot about half way. it doesn't move all the way out to the end of the slot and leaves about 3/8" space left (if that makes sense). It seems like the clutch disc is stuck the flywheel but not the pressure plate.

does that diagnosis seem correct?

if so, what is the best way to break the clutch disc free from the flywheel?

The proper answer is probably replace the clutch and surface the flywheel. I had one stuck on a blazer once and chained it to a pole, depressed the clutch then hit the starter and broke it free. It worked for the short while i owned it after that but I never trusted it.

Block the clutch pedal down with a piece of 2X4 between the seat frame and the pedal, and drive a wide putty knife between the clutch disc and the flywheel. If that doesn't want to work, you might have to pull the transmission and the pressure plate to free up the disc.
Jerry

I have had success in years past with putting the truck in gear, turn the ignition on and push start with another vehicle. The inertia of the flywheel usually breaks the stuck disc loose. Be ready to blip the throttle and pull it back into neutral if it doesn’t. Don’t give up on the first try. Good luck.

Option #1: pull with a strong truck or tractor with trans in gear and ignition off---engine will be spinning. Pump clutch pedal.

Option #2: start in gear if it will. Hold clutch pedal down and floor gas pedal and then hit brakes hard, repeat.

If the lazy way doesn't work follow Jerry's method.

Jack up one wheel and start it. Then depress the clutch and have someone push it off the jack. Something will give - hopefully the clutch.

Thus has happened to me several times. I've done all the solutions above with success. However I found another one.
Start the truck in neutral and let it idle for 15 to 30 minutes. The heat from the exhaust will loosen the grip and let it disengage.

I just went through this with my '38. I used coilover's solution #2 with the exception of not slamming on the brakes. I made sure everything was clear behind me and started in reverse while holding the clutch pedal in. I rolled out of the garage to the road. I slid into neutral while straightening the steering up in the road. I put it in first then started it again, That was enough to brake the clutch loose for me. Keep in mind you've got to be holding the clutch pedal in while doing all of this. You might have to accelerate and decelerate a few times to get it to break loose. If this doesn't do the job you'll probably have to mechanically pry it apart. When mine finally came unstuck I drove it around for a while, slipping the clutch some to wear off what caused it to stick. I will make sure to drive it more often to prevent it from happening again.

As with everything, if it sets it deteriorates!

Do what HRL said, sounds like the safest.