Did i damage my 727

I have personally never seen the park pawl break but I would imagine if it was thrown in park at any reasonable speed its going to lock the rear tires and skid or snap off the pawl. The bigger tires you have the more chance something got damaged.
To pull the tailshaft you need to drop the crossmember and remove the mount. Put a jack under the pan so you can let the trans tilt down. Remove the tailshaft bolts and you will also have to remove a plate that is under the trans mount. Inside there is a clip that needs to be spread while sliding the housing off. The clip locks the output shaft bearing to the case.
Obviously you will need to remove the drive shaft and speedo cable/drive. Your going to loose some fluid so either drain it before or just put a pan to catch it.
You can check the park mech for proper operation without pulling anything.