Two men were injured when their white Vauxhall van overturned on a left-hand bend on Thwaites Lane at around 9.30am on Friday 4 November 2011.
While travelling towards the A61, the van had to veer onto the muddy grass verge at the side of the road to avoid an oncoming vehicle which was heading towards Markington.
Police would like to trace the vehicle which is believed to be a black VW or Mercedes van with green signage on its sides.
Traffic Constable Stuart Holden, of Harrogate Roads Policing Group, said:
Fortunately the occupants of the white van were not seriously injured in the incident, which could have turned out much worse than it did.
I am appealing to the driver of the black van to do the right thing and come forward to help us with our enquiries.
I would also appeal to anyone else who witnessed the incident to contact the police with any information that can assist the investigation.
Anyone who can help the police with their enquiries is urged to contact TC Stuart Holden, of Harrogate police, on 0845 60 60 24 7, quoting reference number 12110187122.