The collision occurred at 3.30pm on Monday 15 October 2012 and involved a grey Nissan Almera, a blue Land Rover Freelander and a blue MG ZR .
Officers would particularly like to speak to the driver of a tractor which was parked at the approach to the junction of the road from Arkendale which joins the A168.
The driver of the MG, an 28-year-old woman from the Knaresborough area sustained a facial injury during the collision and was treated at York District Hospital.
The driver and passenger in the Nissan, a man, 75 and a woman, 74, both from a village in the Thirsk area were taken to Harrogate District Hospital for treatment to chest injuries. All casualties have since been released from hospital. The occupant of the Freelander was uninjured.
Police would like to hear from the tractor driver or anyone else who was in the area at the time and witnessed the collision or saw any of the vehicles prior to impact.
If you are the tractor driver, or can assist the police with any information about the collision, please contact the investigating officer, Traffic Constable Steve James of Harrogate Roads Policing Group, by calling 101, select option 2 and ask for Steve James, or you can pass information via email to email@example.com