If the foot end of your stretcher touches the lock down bar before the lock post comes in contact with the pin on the lockdown rail, you need to adjust the angle of the lock bar. You can do this with the 'Wedge'. It may require longer screws than in original You may need hardware (SK-7002-H).
The 'J' hook has become the standard safety stop block. It give several extra inches so that the stretcher wheels do not hit the bumper when unloading. Mounting hardware is avaiable but not included.