ahh its an onroad shaft drive.
start by turning the spur by hand and watching the driveline. you dont have a trans so it should be clutch bell to spur, and spur on the center driveshaft. make sure the center shaft turns, then look at the outdrives to the wheels. see if they turn.
it could be a loose grub screw on a shaft, a stripped wheel, wheel nut, or broke pin, or a diff.