After the gear was selected down, no down indication was received for the right gear leg. The pilot decided to divert to Port Hedland where engineering advice was available. When it was decided that all the options were exhausted, the pilot landed the aircraft. As the right wheel contacted the ground the leg collapsed and the aircraft slid to a stop. The right maingear retract ram had become disconnected from the body of the gear leg when an improperly secured clevis caused the failure of the body fitting to which it was connected. The components had been incorrectly assembled during previous maintenance.
