Can you put the front axle up so a clearance of couple inches from level area. under the engine is a slide tube covering the propreller shaft to the front end check if a pin is broken in coupling and so disconnected from the front end. if the shaft appears good and still no 4 whl drive possible pinion gear in housing. Check for axle pin wear where the frame to the axle rides should not be able to rock forward or back ward This causes binding in propeller shaft causes breakage. My l3600 never made it to 1500 hours before developing front end problems.
ken