Locked in gear can mean a lot of different things. Do you mean the shifter won't move to change gears. Or the shifter works fine, but will smoke the belt if you let the clutch out.
Not locked in gear the wheels are turning but one wheel turns forward the other turns backward
#4
ILENGINE
That means the differential is working correctly. Now if you are pushing it and it is skidding one wheel in reverse, it either isn't in neutral or the parking brake is stuck.
