Mr Hubbard later died from injuries received when the car being driven by Mrs Hubbard, heading south, and a four wheel drive truck towing a trailer, heading north, collided about 1pm near the 45 Parallel plaque.
Police received information a truck and trailer unit was travelling south about the time of the crash and want to contact its driver.
"We would be keen to hear the driver's account of the crash is they did see it take place and ask them to get in contact with police," Oamaru Detective Kevin Kirkman said today.
No detailed description of the truck and trailer unit was available, but it was possible because of the height of the cab the driver may have had a view at a distance of the crash.
Investigations into the crash are expected to take a few more weeks as police complete crash analysis work.
The coroner had also requested a full report into the cause of the crash.
A number of witnesses had already come forward with information, he said.
